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Troff User`s Manual&dagger;

1. 1 in font B The width function also sets three number registers The registers st and sb are set respectively to the highest and lowest extent of string relative to the baseline then for example the total height of the string is n stu n sbu In troff the number register ct is set to a value between 0 and 3 The value 0 means that all of the characters in string were short lower case characters without descenders like e 1 means that at least one character has a descender like y 2 means that at least one character is tall like H and 3 means that both tall characters and characters with descenders are present 11 3 Mark horizontal place The function kx causes the current horizontal position in the input line to be stored in register x For example the construction kxword h nxut 3u word will embolden word by backing up to almost its beginning and overprinting it resulting in word 12 Overstrike Bracket Line drawing Graphics and Zero width Functions 12 1 Overstriking Automatically centered overstriking of up to nine characters is provided by the over strike function o string The characters in string are overprinted with centers aligned the total width is that of the widest character string may not contain local vertical motion As examples o e pro duces and o mo s1 produces 12 2 Zero width characters The function zc will output c without spacing over it and c
2. if s1 s2 any If string s1 not identical to s2 accept any le c any 5 el any 5 17 Environment Switching ev N N 0 previous 18 Insertions from the Standard Input rd prompt prompt BEL ex 7 z 19 Input Output File Switching so filename nx filename end of file sy string pi string cf filename 20 Miscellaneous mc c N off tm string newline ab string newline ig yy 5 yy LEN f pm t all SEL 2 21 Output and Error Messages 22 Output Language 23 Device and Font Description Files If portion of if else all above forms like if Else portion of if else Environment switch push down Read insertion Exit Switch source file push down Next file Execute program string Output is not interpolated Pipe output to program string Copy file contents to troff output Set margin character c and separation N Print string on terminal standard error Print string on standard error exit program Ignore input until call of yy Set input line number to N and filename to f Print macro names sizes if t present print only total of sizes Flush output buffer Alphabetical Request and Section Number Cross Reference ab 20 ce 4 ec 10 fe 2 ad 4 cf 19 el 16 he 13 af 8 ch J em 7 hw 13 am 7 es 2 eo 10 hy 13 as 7 cu 10 ev 17 ie 16 bd 2 da 7 ex 18 if 16 bp 3 de 7 fc 9 ig 20 br 4 di 7 fi 4 in 6 c2 10 ds 7 fl 20 Lt 7 cc 10 dt 7 fp 2 lc 9 lg
3. 10 point 12 36m off off off Roman R I B S lli N 1 N 1 1i 0 none none previous ignored previous ignored lli ignored previous N lv internal internal 4 Text Filling Adjusting and Centering 5 Vertical Spacing pl N bp N pn N po N ne N mk R rt tN br fi SRE ad c na ce N vs N ls N sp N sv N OS ns rs fill fill adj both adjust off 12p 1 6i N 1 space 6 Line Length and Indenting 1l1l N in N ti tN 6 51 N 0 previous previous N lv N lv previous previous ignored Argument Notes E T E T P T P T P T B v D v Em B E m B E m Explanation Point size also s N Space character size set to N 36 em Constant character space width mode font F Embolden font F by N 1 units Embolden Special Font when current font is F Change to font F also f x xx EN Mount font named F on physical position N 2 1 long name is L if given Page length Eject current page next page number N Next page number N Page offset Need N vertical space Mark current vertical place in register R Return upward only to marked vertical place Break Fill output lines No filling or adjusting of output lines Adjust output lines with mode c c 1 r c b none No output line adjusting Center next N input text lines Vertical baseline spacing V Output N 1 v s after each text output line Space
4. amp Still another way is to specify out put translation of some convenient character into the control character using t r 10 5 4 2 Interrupted text The copying of a input line in nofill non fill mode can be interrupted by terminat ing the partial line with a c The next encountered input text line will be considered to be a continuation of the same line of input text Similarly a word within filled text may be interrupted by terminating the word and line with c the next encountered text will be taken as a continuation of the interrupted word If the intervening control lines cause a break any partial line will be forced out along with any partial word br z B Break The filling of the line currently being collected is stopped and the line is output with out adjustment Text lines beginning with space characters but not tabs and empty text lines blank lines also cause a break afi fill on B E Fill subsequent output lines The register u is 1 in fill mode and 0 in nofill mode nf fill on BE Nofill Subsequent output lines are neither filled nor adjusted Input text lines are copied directly to output lines without regard for the current line length adc adj both adjust E Line adjustment is begun If fill mode is not on adjustment will be deferred until fill mode is back on If the type indicator c is present the adjustment type is changed as shown in the following table Indicator Adjust Type 1 ad
5. A reasonable value for N is 3 when the character size is near 10 points If N is missing the embolden mode is turned off The emboldening value N is in the b reg ister This paragraph is printed with bd R 3 The mode must be in effect when the charac ters are physically printed Ignored in nroff bd S FN off P The characters in the Special font will be emboldened whenever the current font is F The The fields have the same meaning as described earlier in the Request Summary STEEF fp NFL mode must be in effect when the characters are physically printed Ignored in nroff Roman previous E Font changed to F Alternatively embed F The font name P is reserved to mean the pre vious font and the name S for the special font R I B S ignored Font position This is a statement that a font named F is associated with position N Itis a fatal error if F is not known For fonts with names longer than two characters L refers to the long name and F becomes a synonym There is generally a limit of about 10 mounted fonts 3 Page control Top and bottom margins are not automatically provided it is conventional to define two macros and to set traps for them at vertical positions 0 top and N distance N up from the bottom See 7 and Tuto rial Examples T2 A pseudo page transition onto the first page occurs either when the first break occurs or when the first non diverted text processing occurs Arrangement
6. newline are interpreted in copy mode 7 2 Section Reference 3 11 2 7A 7A 15 4 1 11 2 11 2 Section Reference 19 73 5 2 2 3 20 7A 22 20 4 11 1 6 4 2 4 1 6 5 1 4 3 3 dS 2 3 Register Name Register Name S NEM ESS SFHHWDOOSD HE RUE ES Pho ob 8 Predefined Number Registers Description Current page number Character type set by w function Width maximum of last completed diversion Height vertical size of last completed diversion Current day of the week 1 7 Current day of the month 1 31 Output line number Current month 1 12 Vertical position of last printed text baseline Depth of string below baseline generated by w function Height of string above baseline generated by w function Last two digits of current year Predefined Read Only Number Registers Description Process id of troff or nroff Number of arguments available at the current macro level Post line extra line space most recently used in x N Set to 1 in troff if a option used always 1 in nroff Emboldening level Number of lines read from current input file Current vertical place in current diversion equal to n1 if no diversion Current font number Current input file name sic Text baseline high water mark on current page or diversion Available horizontal resolution in basic units Current indent Current ad mode Current output
7. being forced into uses that were never conceived of in the original design all with considerable grace under fire The current version of troff has profited from significant code improvements by Jaap Akkerhuis Dennis Ritchie Ken Thompson and Molly Wagner Andrew Hume Doug McIlroy and Ravi Sethi made valuable suggestions on the manual I fear that the remaining bugs are my fault Usage Troff or nroff is invoked as troff options files nroff options files where options represents any of a number of option arguments and files represents the list of files contain 6 ing the document to be formatted An argument consisting of a single minus is taken to be a filename corresponding to the standard input If no filenames are given input is taken from the standard input The options which may appear in any order so long as they appear before the files are N Run as nroff default is troff mname Read the macro file usr lib tmac name before the input files Tname Specifies the type of the output device Specific devices are site dependent For troff useful names include post Postscript the default 202 Linotron 202 and aps Autologic APS 5 For nroff useful names include 37 for the default Model 37 Teletype 450 for the DASI 450 Diablo Hyterm 1p for dumb line printer terminals no half line motions no reverse motions and think for the HP ThinkJet printer i Read standard input after the input
8. by an increase in page length Two traps may be planted at the same position only by first planting them at different positions and then moving one of the traps the first planted trap will conceal the second unless and until the first one is moved see Tuto rial Examples If the first one is moved back it again conceals the second trap The macro associated with a page trap is automatically invoked when a line of text is output whose vertical size reaches or sweeps past the trap position Reaching the bottom of a page springs the top of page trap if any provided there is a next page The distance to the next trap position is available in the t register if there are no traps between the current position and the bottom of the page the distance returned is the distance to the page bottom Fs A macro invocation trap effective in the current diversion may be planted using dt The t register works in a diversion if there is no subsequent trap a large distance is returned For a description of input line count traps see it below de xx yy am xx yy ds xx string as xx string e OM XX EN xx yy di xx da xx wh N xx chxx N dt N xx Lit Nxx OM XX wy Define or redefine the macro xx The contents of the macro begin on the next input line Input lines are copied in copy mode until the definition is terminated by a line beginning with yy whereupon the macro yy is called In the absence of yy the
9. device The output language contains information that was not readily identifiable in the older output Most notably the beginning of each page and line is marked so post processors can do device specific optimiza tions such as sorting the data vertically or printing it boustrophedonically independent of troff Capabilities for graphics have been added troff now recognizes commands for drawing diagonal lines circles ellipses circular arcs and quadratic B splines there are also ways to pass arbitrary informa tion to the output unprocessed by troff A number of limitations have been eased or eliminated A document may have an arbitrary number of fonts on any page if the output device permits it of course Fonts may be accessed merely by naming This is a version of the original troff reference manual revised several times by B W Kernighan them mounting is no longer necessary There are no limits on the number of characters Character height and slant may be set independently of width The remainder of this document contains a description of usage and command line options a sum mary of requests escape sequences and pre defined number registers a reference manual tutorial exam ples and a list of commonly available characters Acknowledgements Joe Ossanna s troff remains a remarkable accomplishment For fifteen years it has proven a robust tool taking unbelievable abuse from a variety of preprocessors and
10. driving table prepared for each device 2 2 Fonts Troff begins execution by reading information for a set of defaults fonts said to be mounted conventionally the first four are Times Roman R Times Italic 1 Times Bold 8 and Times Bold Italic BI and the last is a Special font S containing miscellaneous characters These fonts are used in this document The set of fonts and positions is determined by the device description file described in 23 The current font initially Roman may be changed by use of the ft request or by embedding at any desired point either fx f xx or N where x and xx are the name of a font and N is a numerical font position It is not necessary to change to the Special font characters on that font are automatically handled as if they were physically part of the current font The Special font may actually be several fonts the name S is reserved and is generally used for one of these All special fonts must be mounted after regular fonts Troff can be informed that any particular font is mounted by use of the fp request The list of known fonts is installation dependent In the subsequent discussion of font related requests F represents either a one two character font name or the numerical font position The current font is available as a numerical position in the read only number register f J A request for a named but not mounted font is honored if the font description information exi
11. files are exhausted olist Print only pages whose page numbers appear in list which consists of comma separated numbers and number ranges A number range has the form N M and means pages N through M a initial N means from the beginning to page N and a final N means from N to the end nN Number first generated page N raN Set number register a one character to N sN Stop every N pages Nroff will halt prior to every N pages default N 1 to allow paper loading or changing and will resume upon receipt of a newline Troff will include a pause code every N pages its meaning if any depends on the output device uN Set amount of emboldening for the bd request to N Fpath Look in directory path for font information default is usr lib font for troff and usr lib term for nroff troff Only a Send a printable ASCII approximation of the results to the standard output nroff Only e Produce equally spaced words in adjusted lines using full terminal resolution h Use tabs instead of spaces to speed up printing q Invoke the simultaneous input output mode of the rd request Each option is a separate argument for example troff Tpost ms 04 6 8 10 filel file2 requests formatting of pages 4 6 and 8 through 10 of a document contained in the files named file1 and file2 specifies the output device as a Postscript printer and invokes the macro package ms Various pre and post proces
12. line argument Tname The default device name is post for Postscript The pre defined string T contains the name of the device The F command line option may be used to change the default directory 23 1 Device description file The file DESC in usr lib font devname contains general parame ters of the device one per line as a sequence of names and values Troff recognizes these parameters and ignores any others that may be present for specific drivers fontsnF F Fy sizes Ss S2 0 res n horn vert n unitwidth n charset list of multi character character names optional The F are font names to be initially mounted The list of sizes is a set of integers representing some or all of the legal sizes the device can produce terminated by a zero The res parameter gives the resolution of the machine in units per inch hor and ver give the minimum number of units that can be moved horizon tally and vertically Character widths for each font are assumed to be given in machine units at point size unitwidth In other words a character with a width of n is n units wide at size unitwidth A list of valid character names may be introduced by charset the list of names is optional A line whose first non blank character is is a comment Except that charset must occur last parameters may appear in any order Here is a subset of the DESC file for a typical Postscript printer Description file for Post
13. line with 11 Local Horizontal and Vertical Motions and the Width Function 11 1 Local Motions The functions v N and h N can be used for local vertical and horizontal motion respectively The distance N may be negative the positive directions are rightward and downward A local motion is one contained within a line To avoid unexpected vertical dislocations it is necessary that the net vertical local motion within a word in filled text and otherwise within a line balance to zero The above and certain other escape sequences providing local motion are summarized in the following table Vertical Effect in Horizontal Effect in Local Motion troff nroff Local Motion troff nroff v N Move distance N h N Move distance N space Unpaddable space size space u 2 em up 2 line up 0 Digit size space d 7 em down line down Ne 1 em up 1 line up 1 6 em space ignored Ae 1 12 em space ignored As an example E could be generated by the sequence E s 2 v 0 4m 2 v 0 4m s 2 note that the 0 4 em vertical motions are at the smaller size 11 2 Width Function The width function w string generates the numerical width of string in basic units Size and font changes may be embedded in string and will not affect the current environment For example ti w fB1 u could be used to temporarily indent leftward a distance equal to the size of the string
14. name is a synonym for the previous char acter The ascender descender field is 1 if the character has a descender hangs below the baseline like y is 2 if it has an ascender is tall like Y is 3 if both and is 0 if neither The value is returned in the ct reg ister as computed by the w function 11 2 Here are excerpts from a typical font description file for the same Postscript printer hy 33 0 45 hyphen hy n is a synonym for hy Q 72 3 81 a 44 0 97 b 50 2 98 44 0 99 d 50 2 100 y 50 1 121 em 100 0 208 Soe 44 2 220 English pound currency symbol N 220 Seu 36 0 221 centered dot N 221 This says for example that the width of the letter a is 44 units at point size 10 the value of unitwidth Point sizes are scaled linearly and rounded so the width of a will be 44 at size 10 40 at size 9 35 at size 8 and so on 231 Tutorial Examples Introduction It is almost always necessary to prepare at least a small set of macro definitions to describe a document Such common formatting needs as page margins and footnotes are deliberately not built into nroff and troff Instead the macro and string definition number register diversion envi ronment switching page position trap and condi tional input mechanisms provide the basis for user defined implementations For most uses a standard package like ms or mm is the right choice The next stage is to augment that or to se
15. number M are to be printed the others will appear as blank number fields omtNM SI off E Line number mode If N is given line numbering is turned on and the next output line numbered is numbered N Default values are M 1 S 1 and J 0 Parameters corre sponding to missing arguments are unaffected a non numeric argument is considered miss ing In the absence of all arguments numbering is turned off the next line number is pre served for possible further use in number register 1n nn N N 1 E The next N text output lines are not numbered 9 As an example the paragraph portions of this section are numbered with M 3 nm 1 3 was placed at the beginning nm was placed at the end of the first paragraph and nm 0 was placed in front of this paragraph and nm finally placed at the end Line lengths were also changed by 12 w 0000 u to keep the right side aligned Another example is nm 5 5 x 3 which turns on num bering with the line number of the next line to be 5 greater than the last numbered line with M 5 with spacing S untouched and with the indent J set to 3 16 Conditional Acceptance of Input In the following c is a one character built in condition name signifies not N is a numerical expression string and string2 are strings delimited by any non blank non numeric character not in the strings and anything represents what is conditionally accepted if c anything If condition c true accept anyt
16. vertical distance N in either direction Save vertical distance N Output saved vertical distance Turn no space mode on Restore spacing turn no space mode off Line length Indent Temporary indent 7 Macros Strings Diversion and Position Traps de xx yy wy Define or redefine macro xx end at call of yy am xx yy yy Append to a macro ds xx string ignored Define a string xx containing string as xx string ignored Append string to string xx rm xx ignored Remove request macro or string rn xx yy ignored Rename request macro or string xx to yy di xx end D Divert output to macro xx da xx end D Divert and append to xx wh N xx v Set location trap negative is w r t page bottom ch xx N v Change trap location dt N xx off D v Set a diversion trap Lit N xx off E Set an input line count trap em xx none none End macro is xx 8 Number Registers nr R N M u Define and set number register R auto increment by M af R c arabic Assign format to register R c 1 i I a A rr R Remove register R 9 Tabs Leaders and Fields ta Nt 0 51 0 8n none Em Tab settings left adjusting unless t R right C centered ste E none none E Tab repetition character sle none E Leader repetition character fc a b off off Set field delimiter a and pad character b 10 Input and Output Conventions and Character Translations ec cC S
17. Column Output The production of multiple column pages requires the footer macro to decide whether it was invoked by other than the last column so that it will begin a new column rather than produce the bottom margin The header can initialize a col umn register that the footer will increment and test The following is arranged for two columns but is easily modified for more de hd header ne EL OF T mk init column count mark top of text 33 de fo footer ie nt cl lt 2 po 3 4i next column 3 1 0 3 rE back to mark ns no space mode el po nMu restore left margin bp REEE E ik column width nr M n 0o save left margin Typically a portion of the top of the first page contains full width text the request for the nar rower line length as well as another mk would be made where the two column output was to begin Footnotes The footnote mechanism to be described is used by embedding the footnotes in the input text at the point of reference demarcated by an initial fn and a terminal ef fn Footnote text and control lines ef In the following footnotes are processed in a sep arate environment and diverted for later printing in the space immediately prior to the bottom mar gin There is provision for the case where the last collected footnote doesn t completely fit in the available space de hd header nr x O01 nr y O nb ch fo nb
18. D is the distance to the diversion trap if any or is very large none internal D Mark the current vertical place in an internal register both associated with the current diver sion level or in register R if given See rt request none internal D v Return upward only to a marked vertical place in the current diversion If N with respect to current place is given the place is N from the top of the page or diversion or if N is absent to a place marked by a previous mk The sp request 5 3 may be used in all cases instead of rt by spacing to the absolute place stored in a explicit register e g using the sequence mk R sp nRu this also works when the motion is downwards 13 4 Text Filling Adjusting and Centering 4 1 Filling and adjusting Normally words are collected from input text lines and assembled into a out put text line until some word does not fit An attempt is then made to hyphenate the word to put part of it into the output line The spaces between the words on the output line are then increased to spread out the line to the current line length minus any current indent A word is any string of characters delimited by the space character or the beginning end of the input line Any adjacent pair of words that must be kept together neither split across output lines nor spread apart in the adjustment process can be tied together by separating them with the unpaddable space character backsla
19. EF 11 ls lt mc mk na ne nf 10 20 6 5 14 20 Rw BW nh 13 pm 20 so 19 tr 10 nm 15 pn 3 sp 5 uf 10 nn 15 po 3 ss 2 ul 10 nr 8 ps 2 sv 5 vs 5 ns 5 rd 18 sy 19 wh 7 nx 19 rm 7 ta 9 os 5 rn 7 te 9 pe 14 rr 8 ti 6 pi 19 S tl 14 pl 3 rt 3 tm 20 Escape Sequences for Characters Indicators and Functions Section Reference 10 1 10 1 2 1 2 1 2 1 ds 11 1 11 1 11 1 11 1 4 1 10 6 10 8 13 ZA 7 1 71 3 9 1 12 3 4 2 2 1 11 1 12 5 2 2 11 1 2 3 11 3 12 4 12 4 2 1 12 1 4 1 11 1 2 3 22 9 1 11 1 11 1 11 2 5 2 10 7 12 2 16 16 10 8 Escape Sequence AN e W NA ee space XO amp aM xx x xx N a b abc e C xyz d ND heeg fx f xx N gx g xx h N H N kx I Nc L Ne nx n xx N N o abe p r sN stN S N NE u v N w string x N X string ze newline Z Meaning prevents or delays the interpretation of Printable version of the current escape character acute accent equivalent to aa grave accent equivalent to ga Minus sign in the current font Period dot see de Unpaddable space size space character Digit width space 1 6 em narrow space character zero width in nroff 1 12 em half narrow space character zero width in nroff Non printing zero width character Tr
20. Revised November 1992 AT amp T Bell Laboratories Murray Hill New Jersey 07974 Computing Science Technical Report No 54 Troff User s Manual Joseph F Ossanna Brian W Kernighan Troff User s Manualt Joseph F Ossanna Brian W Kernighan AT amp T Bell Laboratories Murray Hill New Jersey 07974 Revised November 1992 Troff User s Manualt Joseph F Ossanna Brian W Kernighan AT amp T Bell Laboratories Murray Hill New Jersey 07974 Introduction Troff and nroff are text processors that format text for typesetter and typewriter like terminals respectively They accept lines of text interspersed with lines of format control information and format the text into a printable paginated document having a user designed style Troff and nroff offer unusual free dom in document styling arbitrary style headers and footers arbitrary style footnotes multiple automatic sequence numbering for paragraphs sections etc multiple column output dynamic font and point size control arbitrary horizontal and vertical local motions at any point and a family of automatic overstriking bracket construction and line drawing functions Troff produces its output in a device independent form although parameterized for a specific device troff output must be processed by a driver for that device to produce printed output Troff and nroff are highly compatible with each other and it is almost always possible to prepare input acceptab
21. The prespacing parameter is suitable for troff a larger space at least as big as the output device vertical resolution would be more suitable in nroff The choice of remaining space to test for in the ne is the smallest amount greater than one line the V is the available vertical resolution A macro to automatically number section headings might look like section i force font sp 0 4 prespace ene 2 4 n Vu want 2 4 lines SE ai nt s de sc ele phe iS 2022 Mind ES The usage is sc followed by the section head ing text followed by pg The ne test value includes one line of heading 0 4 line in the fol lowing pg and one line of the paragraph text A word consisting of the next section number and a period is produced to begin the heading line The format of the number may be set by af 8 Another common form is the labeled indented paragraph where the label protrudes left into the indent space de lp labeled paragraph pg ein 0 54 paragraph indent wa O62 05A label paragraph ti 0 flow into paragraph t 1 t c The intended usage is 1p label label will begin at 0 2 inch and cannot exceed a length of 0 3 inch without intruding into the paragraph The label could be right adjusted against 0 4 inch by setting the tabs instead with ta 0 4iR 0 5i The last line of lp ends with c so that it will become a part of the first line of the text that follows Multiple
22. al character width which is output device dependent common values are 1 10 and 1 12 inch Actual character widths in nroff need not be all the same and constructed characters such as gt are often extra wide The default scaling is m for the horizontally oriented requests and functions 11 in ti ta 1t po mc h 1 and horizontal coordi nates of D v for the vertically oriented requests and functions pl wh ch dt sp sv ne rt v x L and vertical coordinates of D p for the vs request and u for the requests nr if and ie All other requests ignore any scale indicators When a number register containing an already appropriately scaled number is interpolated to provide numerical input the unit scale indicator u may need to be appended to prevent an additional inappropriate default scaling The number N may be specified in decimal fraction form but the parameter finally stored is rounded to an integer number of basic units Internal computations are performed in integer arithmetic The absolute position indicator may be prepended to a number N to generate the distance to the vertical or horizontal place N For vertically oriented requests and functions N becomes the distance in basic units from the current vertical place on the page or in a diversion 7 4 to the vertical place N For all other requests and functions N becomes the distance from the current horizontal place on the input line 10 to the horizo
23. an be input with the sequence The escape character can be changed with ec and all that has been said about the default becomes true for the new escape character e can be used to 20 print whatever the current escape character is The escape mechanism may be turned off with eo and restored with ec Lecce Set escape character to or to c if given e0 on Turn escape mechanism off 10 2 Ligatures The set of available ligatures is device and font dependent but is often a subset of fi fl ff ffi and ffl They may be input by fi 1 f Fi and F1 respectively The ligature mode is normally on in troff and automatically invokes ligatures during input lgN on off on Ligature mode is turned on if N is absent or non zero and turned off if N 0 If N 2 only the two character ligatures are automatically invoked Ligature mode is inhibited for request macro string register or file names and in copy mode No effect in nroff 10 3 Backspacing underlining overstriking etc Unless in copy mode the ASCII backspace character is replaced by a backward horizontal motion having the width of the space character Underlining as a form of line drawing is discussed in 12 4 A generalized overstriking function is described in 12 1 Nroff automatically underlines characters in the underline font specifiable with uf normally that on font position 2 In addition to ft and fF the underline font may be se
24. an be used to produce left aligned overstruck combinations As examples z ci pl will produce and 22 or z rn ul br will produce a small constructed box 12 3 Large Brackets The Special Font usually contains a number of bracket construction pieces fl 34 1 L T that can be combined into various bracket styles The function b string may be used to pile up vertically the characters in string the first character on top and the last at the bottom the characters are vertically separated by 1 em and the total pile is centered 1 2 em above the current baseline line in nroff For example b 1lc LE END ec vf x 0 5m yx 0 5m produces fe 12 4 Line drawing The function 1 Nc backslash ell draws a string of repeated c s towards the right for a distance N If c looks like a continuation of an expression for N it may be insulated from N with a amp If cis not specified the _ baseline rule is used underline character in nroff If N is negative a back ward horizontal motion of size N is made before drawing the string Any space resulting from N size of c having a remainder is put at the beginning left end of the string If N is less than the width of c a single c is centered on a distance N In the case of characters that are designed to be connected such as baseline rule _ under rule _ and root en the remainder space is covered by overlapping As an examp
25. ansparent line indicator Beginning of comment continues to end of line Default optional hyphenation character Character named xx Interpolate string x or xx Interpolate argument 1 lt N lt 9 Non interpreted leader character Bracket building function Connect to next input text Character named xyz Downward 1 2 em vertical motion 1 2 line in nroff Draw graphics function c with parameters c 1 c a Change to font named x or xx or position N Format of number register x or xx Local horizontal motion move right N negative left Height of current font is N Mark horizontal input place in register x Horizontal line drawing function optionally with c Vertical line drawing function optionally with c Contents of number register x or xx Character number N on current font Overstrike characters a b c Break and spread output line Reverse em vertical motion reverse line in nroff Point size change function also s mn s nn Slant output N degrees Non interpreted horizontal tab Reverse up 1 2 em vertical motion 1 2 line in nroff Local vertical motion move down N negative up Width of string Extra line space function negative before positive after Ouput string as device control function Print c with zero width without spacing Begin conditional input End conditional input Concealed ignored newline Z any character not listed above The escape sequences S a n t g and
26. arguments to represent a single double quote character The argument is explicitly null If the desired arguments won t fit on a line a concealed newline may be used to continue on the next line A trailing double quote may be omitted When a macro is invoked the input level is pushed down and any arguments available at the previous level become unavailable until the macro is completely read and the previous level is restored A macro s own arguments can be interpolated at any point within the macro with N which interpolates the Nth argument 1 lt N lt 9 If an invoked argument does not exist a null string results For example the macro xx may be defined by de xx begin definition Today is 1 the 2 end definition and called by xx Monday 14th to produce the text Today is Monday the 14th Note that each was concealed in the definition with a prepended The number of arguments is in the register No arguments are available at the top non macro level within a string or within a trap invoked macro Arguments are copied in copy mode onto a stack where they are available for reference It is advis able to conceal string references with an extra to delay interpolation until argument reference time 7 4 Diversions Processed output may be diverted into a macro for purposes such as footnote processing see Tutorial T5 or determining the horizontal and vertical size of some text for conditional chang
27. ation only no action Dc n graphics function c see below x n device control functions see below n comment All position values are in units Sequences that end in digits must be followed by a non digit Blanks tabs and newlines may occur as separators in the input and are mandatory to separate constructions that would otherwise be confused Graphics functions device control functions and comments extend to the end of the line they occur on The device control and graphics commands are intended as open ended families to be expanded as needed The graphics functions coincide directly with the D sequences D1 dh dv draw line from current position by dh dv Ded draw circle of diameter d with left side here Dedh dv2 draw ellipse of diameters dh and dv Da dh dv dh dv draw arc from current position to dh dhy dv dv3 center at dh dv from current position D dh dv dh dv draw B spline from current position to dh dv 28 then to dh dv3 then to Dz dh dv dh dv for any other z is uninterpreted In all of these dh dv is an increment on the current horizontal and vertical position with down and right positive All distances and dimensions are in units The device control functions begin with x then a command then other parameters x Ts name of typesetter is s x r nhv resolution is n units inch h minimum horizontal motion v minimum vertical xsi initialize x f ns mount fon
28. c A number register may be used any time numerical input is expected or desired and may be used in numerical expressions 1 4 Number registers are created and modified using nr which specifies the name numerical value and the auto increment size Registers are also modified if accessed with an auto incrementing sequence If the registers x and xx both contain N and have the auto increment size M the following access sequences have the effect shown Effect on Value Sequence Register Interpolated nx none N n xx none N nt x x incremented by M N M n x x decremented by M N M n xx xx incremented by M N M n xx xx decremented by M N M When interpolated a number register is converted to decimal default decimal with leading zeros lower case Roman upper case Roman lower case sequential alphabetic or upper case sequential alphabetic according to the format specified by af nr RINM u The number register R is assigned the value N with respect to the previous value if any The increment for auto incrementing is set to M af Rce arabic Assign format c to register R The available formats are Numbering Format Sequence 1 0 E234 N 001 000 001 002 003 004 005 i 0 i ii iii iV V T 0 I II MI IV V a 0 a b c Z aa ab ZZ aaa A 0 A B C Z AA AB ZZ AAA An arabic format having N digits specifie
29. ced out In this and other examples requests like bp and sp that normally cause breaks are invoked using the no break con trol character to avoid this When the header footer design contains material requiring independent text processing the environment may be switched avoiding most interaction with the running text A more realistic example would be de hd header if nS gt 1 sp 0 5i 1 tl base at 0 51 StL ses aI centered page number ps restore size Et restore font vs restore vs Psp dn Ot space to 1 0i ns turn on no space mode de fo footer ps 10 set footer header siz sfe R set font vs 12p set baseline spacing if ns 1 sp n pu 0 5i 1 tl base 0 5i up tl first page number bp wh 0 hd wh 1i fo which sets the size font and baseline spacing for the header footer material and ultimately restores them The material in this case is a page number at the bottom of the first page and at the top of the remaining pages The sp s refer to absolute posi tions to avoid dependence on the baseline spac ing Another reason for doing this in the footer is that the footer is invoked by printing a line whose vertical spacing swept past the trap position by possibly as much as the baseline spacing No space mode is turned on at the end of hd to render ineffective accidental occurrences of sp at the top of the running text The abov
30. definition is terminated by a line beginning with A macro may contain de requests provided the terminating mac ros differ or the contained definition terminator is concealed can be concealed as which will copy as and be reread as yy Append to macro xx append version of de ignored Define a string xx containing string Any initial double quote in string is stripped off to per mit initial blanks ignored Append string to string xx append version of ds ignored Remove request macro or string The name xx is removed from the name list and any related storage space is freed Subsequent references will have no effect If many macros and strings are being created dynamically it may become necessary to remove unused ones to recapture internal storage space for newer registers ignored Rename request macro or string xx to yy If yy exists it is first removed end D Divert output to macro xx Normal text processing occurs during diversion except that page offsetting is not done The diversion ends when the request di or da is encountered without an argument extraneous requests of this type should not appear when nested diversions are being used end D Divert appending to macro xx append version of di v Install a trap to invoke xx at page position N a negative N will be interpreted as a distance from the page bottom Any macro previously
31. e ta Nt 0 8 0 5in none E m Set tab stops and types t R right adjusting t C centering t absent left adjusting Troff tab stops are preset every 0 5in nroff every 0 8in The stop values are separated by spaces and a value preceded by is treated as an increment to the previous stop value tcc none none E The tab repetition character becomes c or is removed thus specifying motion lce none E The leader repetition character becomes c or is removed thus specifying motion fcab off off The field delimiter is set to a the padding indicator is set to the space character or to b if given In the absence of arguments the field mechanism is turned off 10 Input and Output Conventions and Character Translations 10 1 Input character translations Ways of inputting the valid character set were discussed in 2 1 The ASCII control characters horizontal tab 9 1 SOH 9 1 and backspace 10 3 are discussed elsewhere The newline delimits input lines In addition STX ETX ENQ ACK and BEL are accepted and may be used as delimiters or translated into a graphic with t r 10 5 All others are ignored The escape character introduces escape sequences which cause the following character to mean another character or to indicate some function A complete list of such sequences is given in the Summary on page 1 The escape character should not be confused with the ASCII control character ESC The escape character c
32. e footer can result in the footnote rereading finishing before reaching the fx trap A good exercise for the student is to com bine the multiple column and footnote mecha nisms The Last Page After the last input file has ended nroff and troff invoke the end macro 7 if any and when it finishes eject the remainder of the page Dur ing the eject any traps encountered are processed normally At the end of this last page processing terminates unless a partial line word or partial word remains If it is desired that another page be started the end macro de en end macro c pp sem en will deposit a null partial word and produce another last page 34 35 Special Character Names The following table lists names for a set of characters most of which have typically been available with troff Not all print on any particular device including this one AUYHDAVDQMMEPUH OOD Qov0ned eed eQqauag GO ON AO ARO ON A ON UE RO QIAO ON A ON lS ON AR OE AE ON EE ON ag OE a ty A GE ig BO Se hee DS Ae a Ae ee Re eS GD _oO ee Gr rrr rv vr vr vr vrvrvrwvr vrwvrvrvrvrvrvrvrwTvrvrwvrvrvrvrvrvrvrvrwvrvrrwr wv Ue eSeERESIMLADNZOLUM lt SZMOKANHHOmMHOS Al Vi il Oo St Nestea atest OO Pp OO det Ox OM Oo GC QOMNT UNNNG ASA DAHA AMNHHH He TOHOOH OVOAE OK XN BOD NK kK kK K K K K kK kK xk x POE FR PE PE POOLE PE POD E A Og PR oP tag gE Gl g a BE PA Gg a fl IXXNNaeH PR 900 he
33. e method of restoring size font etc presupposes that such requests that set pre vious value are not used in the running text A better scheme is save and restore both the current and previous values as shown for size in the fol lowing de fo nx sl n s current size ps nr s2 n s previous size rest of footer de hd header stuff ps n s2 restore previous size ps n sl restore current siz Page numbers may be printed in the bottom mar gin by a separate macro triggered during the footer s page ejection de bn Pp eel eae bottom number centered pag Oo aE numb 235 wh 0 5i lv bn tl base 0 5i up Paragraphs and Headings The housekeeping associated with starting a new paragraph should be collected in a paragraph macro that for example does the desired prepara graph spacing forces the correct font size base line spacing and indent checks that enough space remains for more than one line and requests a temporary indent de pg paragraph br break sft R force font ps 10 size vs 12p spacing ein 0 and indent sp 0 4 prespace ne 1 n Vu want more than 1 line ti 0 2i temp indent The first break in pg will force out any previous partial lines and must occur before the vs The forcing of font etc is partly a defense against prior error and partly to permit things like section heading macros to set parameters only once
34. equest then uses the reverse sense of that state ie e1 pairs may be nested Some examples are if e tl Even Page which outputs a title if the page number is even and ie ns gt 1 d sp 0 5i E tl Page 7 sp 1 2i el sp 2 5i which treats page 1 differently from other pages 17 Environment Switching A numter of the parameters that control the text processing are gathered together into an environ ment which can be switched by the user The environment parameters are those associated with requests noting E in their Notes column in addition partially collected lines and words are in the environment Everything else is global examples are page oriented parameters diversion oriented parameters number registers and macro and string definitions All environments are initialized with default parameter values ev N N 0 previous Environment switched to environment 0 lt N lt 2 Switching is done in push down fashion so that restoring a previous environment must be done with ev rather than specific reference Note that what is pushed down and restored is the environment number not its contents 18 Insertions from the Standard Input The input can be temporarily switched to the system standard input with rd which will switch back when two consecutive newlines are found the extra blank line is not used This mechanism is intended for insertions in form letter like documentation On UNIX the
35. ers to non negative values exceptions are sp wh ch nr and if The requests ps ft po vs ls 11 in and 1t restore the previous parameter value in the absence of an argument Single character arguments are indicated by single lower case letters and one two character argu ments are indicated by a pair of lower case letters Character string arguments are indicated by multi character mnemonics 2 Font and Character Size Control 2 1 Character set The troff character set is defined by a description file specific to each output device 23 There are normally several regular fonts and one or more special fonts Characters are input as themselves ASCII as xx as C name or as N n The form C name permits a name of any length the form N n refers to the n th character on the current font whether named or not Normally the input characters and are printed as and respectively and pro duce and Non existent characters are printed as a 1 em space Nroff has an analogous but different mechanism for defining legal characters and how to print them By default all ASCII characters are valid There are such additional characters as may be available on the output device such characters as may be able to be constructed by overstriking or other combination and those that can reasonably be mapped into other printable characters The exact behavior is determined by a
36. et escape character e0 on Turn off escape character mechanism lg N on on T Ligature mode on if N gt 0 ul N off N 1 E Underline italicize in troff N input lines cu N off N 1 E Continuous underline in nroff in troff like ul uf F Italic Italic Underline font set to F to be switched to by u1 cc Cc E Set control character to c ELC f E Set no break control character to c tr abcd none O Translate a to b etc on output 11 Local Horizontal and Vertical Motions and the Width Function 12 Overstrike Bracket Line drawing Graphics and Zero width Functions 13 Hyphenation nh hyphenate E No hyphenation hy N hyphenate hyphenate E Hyphenate N mode he C E Hyphenation indicator character c hw word ignored Add words to hyphenation dictionary 14 Three Part Titles atl Ver Three part title delimiter may be any character peng off Page number character lt N 6 5i previous E m Length of title 15 Output Line Numbering nm tNMSI off E Number mode on or off set parameters nn N N 1 E Do not number next N lines 16 Conditional Acceptance of Input if c any If condition c true accept any as input for multi line use any if c any If condition c false accept any if N any u If expression N gt 0 accept any if N any u If expression N lt 0O sic accept any if sl s2 any If string s 1 identical to s2 accept any
37. ft center right The strings left center and right are respectively left adjusted centered and right adjusted in the current title length Any of the strings may be empty and overlapping is permitted If the page number character initially is found within any of the fields it is replaced by the current page number in the format assigned to register Any character may be used in place of as the string delimiter PEC off The page number character is set to c or removed The page number register remains 24 1t N 6 5 in previous E m Length of title is set to N The line length and the title length are independent Indents do not apply to titles page offsets do 15 Output Line Numbering Automatic sequence numbering of output lines may be requested with nm When in effect a three digit arabic number plus a digit space is prepended to output text lines The text lines are thus 3 offset by four digit spaces and otherwise retain their line length a reduction in line length may be desired to keep the right margin aligned with an earlier margin Blank lines other vertical spaces and lines generated by t 1 are not numbered Numbering can be temporarily suspended with nn or with 6 an nm followed by a later nm 0 In addition a line number indent Z and the number text separa tion S may be specified in digit spaces Further it can be specified that only those line numbers that are multiples of some
38. g the tab or leader up to the next tab or leader or end of line and W is the width of next string Tab Length of motion or Location of type repeated characters next string Left D Following D Right D W Right adjusted within D Centered D W 2 Centered on right end of D The length of generated motion is allowed to be negative but that of a repeated character string cannot be Repeated character strings contain an integer number of characters and any residual distance is prepended as motion Tabs or leaders found after the last tab stop are ignored but may be used as next string termina tors Tabs and leaders are not interpreted in copy mode t and a always generate a non interpreted tab and leader respectively and are equivalent to actual tabs and leaders in copy mode 9 2 Fields A field is contained between a pair of field delimiter characters and consists of sub strings separated by padding indicator characters The field length is the distance on the input line from the posi tion where the field begins to the next tab stop The difference between the total length of all the sub strings and the field length is incorporated as horizontal padding space that is divided among the indicated padding places The incorporated padding is allowed to be negative For example if the field delimiter is and the padding indicator is xxx right specifies a right adjusted string with the string xxx centered in the remaining spac
39. he current font to N or increments it by N or decrements it by N if N 0 the height is restored to the current point size In each case the width is unchanged Not all devices support independent height and width for characters Request Initial If No Form Value Argument Notes ps tN 10 point previous E Point size set to N Alternatively embed sN or stN Any positive size value may be requested if invalid the next larger valid size will result with a maximum of 36 A paired sequence N N will work because the previous requested value is also remembered Ignored in nroff ssN 12 36em ignored E Space character size i e inter word gap is set to N 36 ems This size is the minimum word spacing in adjusted text Ignored in nroff cs FNM off P Constant character space width mode is set on for font F if mounted the width of every character will be taken to be N 36 ems If M is absent the em is that of the character s point size if M is given the em is M points All affected characters are centered in this space including those with an actual width larger than this space Special Font characters occurring while the current font is F are also so treated If N is absent the mode is turned off The mode must be in effect when the characters are physically printed Ignored in nroff bAa FN off P The characters in font F will be artificially emboldened by printing each one twice separated by N 1 basic units
40. hing as input in multi line case use fanything j if canything If condition c false accept anything if N anything u If expression N gt 0 accept anything if N anything u If expression N lt 0 accept anything if stringl string2 anything If string identical to string2 accept anything if stringl string2 anything If string not identical to string2 accept anything ie c anything u If portion of if else all of the forms for i above are valid el anything X95 Else portion of if else The built in condition names are Condition Name True If o Current page number is odd e Current page number is even Formatter is troff n Formatter is nroff If the condition c is true or if the number N is greater than zero or if the strings compare identically including motions and character size and font anything is accepted as input If a precedes the condi tion number or string comparison the sense of the acceptance is reversed Any spaces between the condition and the beginning of anything are skipped over The anything can be either a single input line text macro or whatever or a number of input lines In the multi line case the first line must begin with a left delimiter and the last line must end with a right delimiter The request ie if else is identical to if except that the acceptance state is remembered A subse quent and matching e1 else r
41. horizontal position Current line length Current 1s value Length of text portion on previous output line Current page offset Current page length Number of unused number registers Set to 1 in nroff if T option used always 0 in troff Current point size Distance to the next trap Equal to 1 in fill mode and 0 in nofill mode Current vertical line spacing Available vertical resolution in basic units Width of previous character Reserved version dependent register Reserved version dependent register Name sic of current diversion 9 Reference Manual 1 General Explanation 1 1 Form of input Input consists of text lines which are destined to be printed interspersed with control lines which set parameters or otherwise control subsequent processing Control lines begin with a control character normally period or single quote followed by a one or two character name that speci fies a basic request or the substitution of a user defined macro in place of the control line The control character suppresses the break function the forced output of a partially filled line caused by certain requests The control character may be separated from the request macro name by white space spaces and or tabs for aesthetic reasons Names should be followed by either space or newline Control lines with unrecognized names are ignored Various special functions may be introduced anywhere in the input by mea
42. ing of pages or columns A single diversion trap may be set at a specified vertical position The number registers dn and d1 respectively contain the vertical and horizontal size of the most recently ended diversion Pro cessed text that is diverted into a macro retains the vertical size of each of its lines when reread in nofill mode regardless of the current V Constant spaced cs or emboldened bd text that is diverted can be reread correctly only if these modes are again or still in effect at reread time One way to do this is to embed in the diversion the appropriate cs or bd requests with the transparent mechanism described in 10 6 Diversions may be nested and certain parameters and registers are associated with the current diver sion level the top non diversion level may be thought of as the Oth diversion level These are the diver sion trap and associated macro no space mode the internally saved marked place see mk and rt the cur rent vertical place d register the current high water text baseline h register and the current diversion name z register 7 5 Traps Three types of trap mechanisms are available page traps a diversion trap and an input line count trap Macro invocation traps may be planted using wh at any page position including the top This trap position may be changed using ch Trap positions at or below the bottom of the page have no effect unless or until moved to within the page or rendered effective
43. ister a e g using mk a as was done for this paragraph 12 5 Graphics The function D c draws a graphic object of type c according to a sequence of param eters which are generally pairs of numbers D 1 dh dv draw line from current position by dh dv XO32 D c d draw circle of diameter d with left side at current position D e didz draw ellipse of diameters d4 and d3 D a dh dv dh dv draw arc from current position to dh dhy dv dv3 with center at dh dv from current position D dh dv dhdv3 draw B spline from current position by dh dv then by dh dv3 then by dh dv3 then For example D e0 2i 0 11 draws the ellipse 4 and D 1 2i 1i D 1 1i 1i the line A D with an unknown c is processed and copied through to the output for unspecified interpreta tion Numbers taken as horizontal first third etc have default scaling of ems vertical numbers second fourth etc have default scaling of Vs 1 3 The position after a graphical object has been drawn is at its end for circles and ellipses the end is at the right side 13 Hyphenation Automatic hyphenation may be switched off and on When switched on with hy several variants may be set A hyphenation indicator character may be embedded in a word to specify desired hyphenation points or may be prepended to suppress hyphenation In addition the user may specify a small li
44. just left margin only xr adjust right margin only c center born adjust both margins absent unchanged The number register j contains the current value of the ad setting its value can be recorded 14 and used subsequently to set adjustment na adjust E Noadjust Adjustment is turned off the right margin will be ragged The adjustment type for ad is not changed Output line filling still occurs if fill mode is on ceN off N 1 BE Center the next N input text lines within the current available horizontal space line length minus indent If N 0 any residual count is cleared A break occurs after each of the N input lines If the input line is too long it will be left adjusted 5 Vertical Spacing 5 1 Baseline spacing The vertical spacing V between the baselines of successive output lines can be set using the vs request V should be large enough to accommodate the character sizes on the affected out put lines For the common type sizes 9 12 points usual typesetting practice is to set V to 2 points greater than the point size troff default is 10 point type on a 12 point spacing as in this document The current V is available in the v register Multiple V line separation e g double spacing may be requested with 1s but it is better to use a large vs instead certain preprocessors assume single spacing The current line spac ing is available in the L register 5 2 Extra line space If a word contains a
45. le a macro to underscore a string can be written de us SI 17 0 al or one to draw a box around a string de bx or SIN I br N 1 0 Cen 17 0 ul such that ul underlined words and bx words in a box yield underlined words and words in a box The function L Nc draws a vertical line consisting of the optional character c stacked vertically apart 1 em 1 line in nroff with the first two characters overlapped if necessary to form a continuous line The default character is the box rule br the other suitable character is the bold vertical bv The line is begun without any initial motion relative to the current baseline A positive N specifies a line drawn downward and a negative N specifies a line drawn upward After the line is drawn no compensating motions are made the instantaneous baseline is at the end of the line The horizontal and vertical line drawing functions may be used in combination to produce large boxes The zero width box rule and the 2 em wide under rule were designed to form corners when using l em vertical spacings For example the macro de eb sp 1 compensate for next automatic baseline spacing nf avoid possibly overflowing word buffer h 5n L nau 1 1 n 1lutin ul L naut 1 1 Ou 5n ul draw box DEI will draw a box around some text whose beginning vertical place was saved in number reg
46. le to both Conditional input is provided that enables the user to embed input expressly des tined for either program Nroff can prepare output directly for a variety of terminal types and is capable of utilizing the full resolution of each terminal A warning however nroff necessarily cannot support all fea tures of troff Within that limitation it is the same as troff and in fact there is only a single program invoked by two different names Background to the Second Edition Troff was originally written by the late Joe Ossanna in about 1973 in assembly language for the PDP 11 to drive the Graphic Systems CAT typesetter It was rewritten in C around 1975 and underwent slow but steady evolution until Ossanna s death late in 1977 In 1979 Brian Kernighan modified troff so that it would produce output for a variety of typesetters while retaining its input specifications Over the decade from 1979 to 1989 the internals have been mod estly revised though much of the code remains as it was when Ossanna wrote it Troff reads parameter files each time it is invoked to set values for machine resolution legal type sizes and fonts and character names character widths and the like Troff output is ASCII characters in a simple language that describes where each character is to be placed and in what size and font A post processor must be written for each device to convert this typesetter independent language into specific instructions for that
47. lected by ul and cu Underlining is restricted to an output device dependent subset of reasonable characters ul N off N 1 E Italicize in troff underline in nroff the next N input text lines Actually switch to underline font saving the current font for later restoration other font changes within the span of a ul will take effect but the restoration will undo the last change Output generated by t 1 14 is affected by the font change but does not decrement N If N gt 1 there is the risk that a trap interpolated macro may provide text lines within the span environment switching can pre vent this cu N off N 1 E Continuous underline A variant of u1 that causes every character to be underlined in nroff Identical to u1 in troff uf F Italic Italic Underline font set to F In nroff F may not be on position 1 10 4 Control characters Both the control character and the no break control character may be changed Such a change must be compatible with the design of any macros used in the span of the change and particularly of any trap invoked macros COC k E ee 99 The basic control character is set to c or reset to c2c t 4 E 6679 The no break control character is set to c or reset to 10 5 Output translation One character can be made a stand in for another character using tr All text processing e g character comparisons takes place with the input stand in character which appears
48. lectively replace macros from the standard package The last stage much harder is to write one s own from scratch The examples discussed here are intended to be useful and somewhat realistic but will not necessarily cover all relevant contingencies Explicit numerical parameters are used in the examples to make them easier to read and to illus trate typical values In many cases number regis ters would really be used to reduce the number of places where numerical information is kept and to concentrate conditional parameter initialization like that which depends on whether troff or nroff is being used Page Margins As discussed in 3 header and footer mac ros are usually defined to describe the top and bot tom page margin areas respectively A trap is planted at page position O for the header and at N N from the page bottom for the footer The simplest such definitions might be de hd define header sp li a end definition de fo define footer rpp tes end definition wh O hd wh 1i fo which provide blank 1 inch top and bottom mar gins The header will occur on the first page only if the definition and trap exist prior to the initial pseudo page transition 3 In fill mode the out put line that springs the footer trap was typically forced out because some part or whole word didn t fit on it If anything in the footer and header that follows causes a break that word or part word will be for
49. lename Set line number to N and filename to filename for purposes of subsequent error messages etc The number register sic F contains the name of the current input file as set by com mand line argument so nx or 1f The number register c contains the number of input lines read from the current file again perhaps as modified by 1f pmt all Print macros The names and sizes of all of the defined macros and strings are printed on the a OT standard error if t is given only the total of the sizes is printed The sizes is given in blocks of 128 characters fe B Flush output buffer Force output including any pending position information 21 Output and Error Messages The output from tm pm and the prompt from rd as well as various error messages are written onto the standard error The latter is different from the standard output where formatted text goes By default both are written onto the user s terminal but they can be independently redirected Various error conditions may occur during the operation of nroff and troff Certain less serious errors having only local impact do not cause processing to terminate Two examples are word overflow caused by a word that is too large to fit into the word buffer in fill mode and line overflow caused by an output line that grew too large to fit in the line buffer In both cases a message is printed the offending excess is discarded and the affected word o
50. m IWC BArOwweods ve
51. ns of an escape character normally For example the function nR causes the interpolation of the contents of the number register R in place of the function here R is either a single character name as in nx or a two character name intro duced by a left parenthesis as in n xx 1 2 Formatter and device resolution Troff internally stores and processes dimensions in units that corre spond to the particular device for which output is being prepared values from 300 to 1200 inch are typical See 23 Nroff internally uses 240 units inch corresponding to the least common multiple of the horizontal and vertical resolutions of various typewriter like output devices Troff rounds horizontal vertical numeri cal parameter input to the actual horizontal vertical resolution of the output device indicated by the T option default post Nroff similarly rounds numerical input to the actual resolution of its output device default Model 37 Teletype 1 3 Numerical parameter input Both nroff and troff accept numerical input with the appended scale indicators shown in the following table where S is the current type size in points and V is the current verti cal line spacing in basic units Scale Indicator Meaning i Inch Centimeter P Pica 1 6 inch m Em S points n En Em 2 p Point 1 72 inch u Basic unit v Vertical line space V none Default see below In nroff both the em and the en are taken to be equal to the nomin
52. ntal place N For example ssp 3 2 will space in the required direction to 3 2 centimeters from the top of the page 1 4 Numerical expressions Wherever numerical input is expected an expression involving parentheses the arithmetic operators mod and the logical operators lt gt lt gt or amp and or may be used Except where controlled by parentheses evaluation of expressions is left to right there is no operator precedence In the case of certain requests an initial or is stripped and interpreted as an increment or decrement indicator respectively In the presence of default scaling the desired scale indicator must be attached to every number in an expression for which the desired and default scaling differ For example if the number register x contains 2 and the current point size is 10 then ell 4 251 nxP 3 2u will set the line length to 1 2 the sum of 4 25 inches 2 picas 3 ems 1 5 Notation Numerical parameters are indicated in this manual in two ways N means that the argu ment may take the forms N N or N and that the corresponding effect is to set the parameter to N to increment it by N or to decrement it by N respectively Plain N means that an initial algebraic sign is not an increment indicator but merely the sign of N Generally unreasonable numerical input is either ignored or truncated to a reasonable value For example most requests expect to set paramet
53. planted at N is replaced by xx A zero N refers to the top of a page In the absence of xx the first trap found at N if any is removed v Change the trap position for macro xx to be N In the absence of N the trap if any is removed off D v Install a diversion trap at position N in the current diversion to invoke macro xx Another dt will redefine the diversion trap If no arguments are given the diversion trap is removed off E Set an input line count trap to invoke the macro xx after N lines of text input have been read control or request lines do not count The text may be inline text or text interpolated by inline or trap invoked macros none none The macro xx will be invoked when all input has ended The effect is almost as if the 18 contents of xx had been at the end of the last file processed but all processing ceases at the next page eject 8 Number Registers A variety of parameters are available to the user as predefined number registers see Summary page 0 In addition users may define their own registers Register names are one or two characters long and do not conflict with request macro or string names Except for certain predefined read only registers a num ber register can be read written automatically incremented or decremented and interpolated into the input in a variety of formats One common use of user defined registers is to automatically number sections paragraphs lines et
54. r line is marked at the point of truncation with a in nroff and a in troff Processing continues if possible on the grounds that output useful for debugging may be produced If a serious error occurs processing terminates and a message is printed along with a list of the macro names currently active Examples of serious errors include the inability to create read or write files and the exceeding of certain internal limits that make future output unlikely to be useful 22 Output Language Troff produces its output in a language that is independent of any specific output device except that the numbers in it have been computed on the basis of the resolution of the device and the sizes fonts and characters that that device can print Nevertheless it is quite possible to interpret that output on a different device within the latter s capabilities sn set point size to n fn set font to n ce print ASCII character c Cxx print character xx terminate xx by white space Nn print character n on current font Hn go to absolute horizontal position n n 20 Vn go to absolute vertical position n n 20 down is positive hn go n units horizontally n lt 0 is to the left vn go n units vertically n lt 0 is up nnc move right nn then print ASCII character c nn must be exactly 2 digits pn new page n begins set vertical position to 0 nba end of line information only no action b space before line a after wW paddable word space inform
55. rest of the input line The output is not collected automatically The number register which contains the process id of the troff process may be useful in generating unique filenames for output pi string Pipe output to string which is the rest of the input line This request must occur before any printing occurs Cf filename Copy contents of file filename to output completely unprocessed The file is assumed to con tain something meaningful to subsequent processes 20 Miscellaneous mce cN off E m Specifies that a margin character c appear a distance N to the right of the right margin after each non empty text line except those produced by t 1 If the output line is too long as can happen in nofill mode the character will be appended to the line If N is not given the previ ous N is used the initial N is 0 2 inches in nroff and 1 em in troff The margin character used with this paragraph was a 12 point box rule tm string newline After skipping initial blanks string rest of the line is read in copy mode and written on the standard error ab string newline After skipping initial blanks string rest of the line is read in copy mode and written on the standard error Troff or nroff then exit ig yy 5 DYE Ignore input lines ig behaves exactly like de 7 except that the input is discarded The input is read in copy mode and any auto incremented registers will be affected 1 N fi
56. s a field width of N digits example 2 above The read only registers and the width function w 11 2 are always arabic Warning the value of a number register in a non arabic format is not numeric and will not produce the expected results in expressions The function gx or g xx returns the format of a number register in a form suitable for af it returns nothing if the register has not been used rrR ignored Remove number register R If many registers are being created dynamically it may become necessary to remove unused registers to recapture internal storage space for newer registers The register R contains the number of number registers still available 19 9 Tabs Leaders and Fields 9 1 Tabs and leaders The ASCII horizontal tab character and the ASCII SOH control A hereafter called the leader character can both be used to generate either horizontal motion or a string of repeated charac ters The length of the generated entity is governed by internal tab stops specifiable with ta The default difference is that tabs generate motion and leaders generate a string of periods tc and 1c offer the choice of repeated character or motion There are three types of internal tab stops left adjusting right adjusting and centering In the following table D is the distance from the current position on the input line where a tab or leader was found to the next tab stop next string consists of the input characters followin
57. s for a trap to occur at the top of the first page must be completed before this transition In the following references to the current diversion 7 4 mean that the mechanism being described works during both ordinary and diverted output the for mer considered as the top diversion level The limitations on troff and nroff output dimensions are device dependent pLiN bp N po EN ne N mk R art iN 1lin llin v Page length set to N The current page length is available in the p register N 1 B v Begin page The current page is ejected and a new page is begun If N is given the new page number will be N Also see request ns N 1 ignored Page number The next page when it occurs will have the page number N A pn must occur before the initial pseudo page transition to affect the page number of the first page The current page number is in the register lin 0 previous v Page offset The current left margin is set to N The troff initial value provides inch of paper margin on a typical device The current page offset is available in the o register N 1 V D v Need N vertical space If the distance D to the next trap position see 7 5 is less than N a forward vertical space of size D occurs which will spring the trap If there are no remaining traps on the page D is the distance to the bottom of the page If D lt V another line could still be output and spring the trap In a diversion
58. script printers fonts 10 R I B BI CW H HB HX S1 S sizes 45 6789101112 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 38 40 44 48 54 60 72 0 res 720 hor 1 vert 1 unitwidth 10 charset hy ct fi fl ff Fi Fl dg em 14 34 12 en aa ga ru sc dd gt br Sl ps cs cy as os ld rd le ge pp ob vr sq bx ci fa te pl mi eq A B X D E F G Y I K L M N O P R H S T U W C Q Z ul rn a b x d e f g y i k x m n xo zp h er xs At xu xw xe q z 23 2 Font description files Each font is described by an analogous description file which begins with parameters of the font one per line followed by a list of characters and widths The file for font f is usr lib font devname f name str name of font is str ligatures 0 list of ligatures spacewidthn width of a space on this font special this is a special font charset 30 list of character name width ascender descender code The name and charset fields are mandatory charset must be last Comments are permitted as are other unrecognized parameters Each line following charset describes one character its name its width in units as described above ascender descender information and a decimal octal or hexadecimal value by which the output device knows it the N number of the character The character name is arbitrary except that signifies an unnamed character If the width field contains the
59. sh space The adjusted word spacings are uniform in troff and the minimum interword spacing can be controlled with the ss request 2 In nroff they are normally nonuniform because of quantization to character size spaces however the com mand line option e causes uniform spacing with full output device resolution Filling adjustment and hyphenation 13 can all be prevented or controlled The text length on the last line output is available in the n register and text baseline position on the page for this line is in the n1 register The text baseline high water mark lowest place on the current page is in the h register The current horizontal output position is in the k register An input text line ending with or optionally followed by any number of or f is taken to be the end of a sentence and an additional space character is automatically provided during filling To prevent this add amp to the end of the input line Multiple inter word space characters found in the input are retained except for trailing spaces initial spaces also cause a break When filling is in effect a p may be embedded or attached to a word to cause a break at the end of the word and have the resulting output line spread out to fill the current line length A text input line that happens to begin with a control character can be made not to look like a control line by prefixing it with the non printing zero width filler character
60. sors are available for use with nroff and troff These include the equa tion preprocessor eqn for troff only the table construction preprocessor tbl and pic ideal and grap for various forms of graphics A reverse line postprocessor col is available for multiple column nroff output on terminals without reverse line ability col expects the Model 37 Teletype escape sequences that nroff produces by default Request Summary In the following table the notation N in the Request Form column means that the forms N N or N are permitted to set the parameter to N increment it by N or decrement it by N respectively Plain N means that the value is used to set the parameter Initial Values separated by are for troff and nroff respectively In the Notes column v p m u Request Form B Hvemy Request normally causes a break The use of as control character instead of Suppresses the break function Mode or relevant parameters associated with current diversion level Relevant parameters are a part of the current environment Must stay in effect until logical output Mode must be still or again in effect at the time of physical output troff only no effect in nroff Default scale indicator if not specified scale indicators are ignored Initial Value 1 General Information If No 2 Font and Character Size Control ps N VSS es bd bd sft fp 2yo Izz i 3 Page Control M N L
61. ss it The footnote start macro fn begins a diversion append in environment 1 and increments the count x if the count is one the footnote separator fs is interpo lated The separator is kept in a separate macro to permit user redefinition The footnote end macro ef restores the previous environment and ends the diversion after saving the spacing size in register z y is then decremented by the size of the footnote available new footer position in dn then on the first footnote y is further decremented by the difference in vertical baseline spacings of the two environments to prevent the late triggering the footer trap from causing the last line of the combined footnotes to overflow The footer trap is then set to the lower on the page of y or the current page position n1 plus one line to allow for printing the reference line If indicated by x the footer fo rereads the footnotes from FN in nofill mode in environment 1 and deletes FN If the footnotes were too large to fit the macro fx will be trap invoked to redi vert the overflow into fy and the register dn will later indicate to the header whether fy is empty Both fo and fx are planted in the nominal footer trap position in an order that causes fx to be concealed unless the fo trap is moved The footer then terminates the overflow diversion if necessary and zeros x to disable fx because the uncertainty correction together with a not too late triggering of th
62. st of exception words Only words that consist of a central alphabetic string surrounded by usually null non alphabetic strings are candidates for automatic hyphenation Words that contain hyphens minus em dashes em or hyphenation indicator characters are always subject to splitting after those characters whether automatic hyphenation is on or off nh hyphenate E Automatic hyphenation is turned off hy N on N 1 on N 1 E Automatic hyphenation is turned on for N 21 or off for N 0 If N 2 last lines ones that will cause a trap are not hyphenated For N 4 and 8 the last and first two characters respectively of a word are not split off These values are additive i e N 14 will invoke all three restrictions hee E Hyphenation indicator character is set to c or to the default The indicator does not appear in the output hw word ignored Specify hyphenation points in words with embedded minus signs Versions of a word with terminal s are implied i e dig it implies dig its This list is examined initially and after each suffix stripping The space available is small about 128 characters 14 Three Part Titles The titling function t 1 provides for automatic placement of three fields at the left center and right of a line with a title length specifiable with 1t t1 may be used anywhere and is independent of the nor mal text collecting process A common use is in header and footer macros tl le
63. standard input can be the user s keyboard a pipe or a file rd prompt prompt BEL z Read insertion from the standard input until two newlines in a row are found If the standard input is the user s keyboard prompt or a BEL is written onto the standard output ra behaves like a macro and arguments may be placed after prompt eX Exit from nroff troff Text processing is terminated exactly as if all input had ended 26 If insertions are to be taken from the terminal keyboard while output is being printed on the terminal the command line option q will turn off the echoing of keyboard input and prompt only with BEL The regular input and insertion input cannot simultaneously come from the standard input As an example multiple copies of a form letter may be prepared by entering the insertions for all the copies in one file to be used as the standard input and causing the file containing the letter to reinvoke itself with nx 19 the process would ultimately be ended by an ex in the insertion file 19 Input Output File Switching SO filename u Switch source file The top input file reading level is switched to filename When the new file ends input is again taken from the original file so s may be nested nx filename end of file Next file is filename The current file is considered ended and the input is immediately switched to filename sy string Execute program from string which is the
64. sts In this way there is no limit on the number of fonts that may be printed in any part of a document Mounted fonts may be handled more efficiently and they may be referred to by their mount positions but there is no other difference The function S N causes the current font to be slanted by N degrees Not all devices support slanting Nroff understands font control and normally underlines italic characters see 10 5 2 3 Character size Character point sizes available depend on the specific output device a typical histor ical set of values is 6 7 8 9 10 11 12 14 16 18 20 22 24 28 and 36 This is a range of 1 12 inch to 1 2 inch The ps request is used to change or restore the point size Alternatively the point size may be changed between any two characters by embedding a sWN at the desired point to set the size to N or a stN 1 lt N lt 9 to increment decrement the size by N sO restores the previous size Requested point size values that are between two valid sizes yield the larger of the two Note that through an accident of history a construction like s39 is parsed as size 39 and thus con verted to size 36 given the sizes above while s40 is parsed as size 4 followed by 0 The syntax s nn and s nn permits specification of sizes that would otherwise be ambiguous The current size is available in the s register Nroff ignores type size requests The function H N sets the height of t
65. t s on font position n x p pause can restart x sS stop done forever x t generate trailer information if any x Ha set character height to n x Sn set slant ton x X any generated by the X function x any to be ignored if not recognized Subcommands like i may be spelled out like init The commands x T x r and x i must occur first fonts must be mounted before they can be used x s comes last There are no other order requirements The following is the output from hello world for a typical Postscript printer as described in 23 x T post x res 720 11 x init vo pl fon fon fon fon fon fon fon fon fon Ww H mo w oN oaoneheWwWNE Q T x Gh cP cer Er oct ech ch cet at MM MH KM KM MH KM OM o n Hh O ct m n lt ha Gem ow as H 0 H720 V120 ch 50e44128128050 w58w72050r33128dn120 0 x trailer V7920 x stop Troff output is normally not redundant size and font changes and position information are not included unless needed Nevertheless each page is self contained for the benefit of postprocessors that re order pages or process only a subset 29 23 Device and Font Description Files The parameters that describe a output device name are read from the directory usr lib font devname each time troff is invoked The device name is provided by default by the environment variable TYPESETTER or by a command
66. til after that line is output In fill mode the length of text on an output line is less than or equal to the line length minus the indent The current line length and indent are available in registers 1 and i respectively The length of three part titles produced by t1 see 14 is independently set by 1t LLIN 6 5in previous Em Line length is set to N initN N 0 previous B E m Indent is set to N The indent is prepended to each output line ti tN ignored B E m Temporary indent The next output text line will be indented a distance N with respect to the current indent The resulting total indent may not be negative The current indent is not changed 7 Macros Strings Diversion and Position Traps 7 1 Macros and strings A macro is a named set of arbitrary lines that may be invoked by name or with a trap A string is a named string of characters not including a newline character that may be interpolated by name at any point Request macro and string names share the same name list Macro and string names may be one or two characters long and may usurp previously defined request macro or string names this implies that built in operations may be irrevocably redefined Any of these entities may be renamed with rn or removed with rm Macros are created by de and di and appended to by am and da di and da cause normal output to be stored in a macro A macro is invoked in the same way as a request a control line beginning x
67. to have the width of the final character The graphic translation occurs at the moment of output including diversion tx abcd none O Translate a into b c into d etc If an odd number of characters is given the last one will be mapped into the space character To be consistent a particular translation must stay in effect from input to output time 10 6 Transparent throughput An input line beginning with a is read in copy mode and transparently 72 output without the initial the text processor is otherwise unaware of the line s presence This mecha nism may be used to pass control information to a post processor or to embed control lines in a macro cre ated by a diversion 10 7 Transparent output The sequence X anything copies anything to the output as a device control function of the form x X anything 22 Escape sequences in anything are processed 10 8 Comments and concealed newlines An uncomfortably long input line that must stay one line e g a string definition or nofilled text can be split into several physical lines by ending all but the last one with the escape The sequence newline is always ignored except in a comment Comments may be embed ded at the end of any line by prefacing them with The newline at the end of a comment cannot be con cealed A line beginning with will appear as a blank line and behave like sp 1 a comment can be on a line by itself by beginning the
68. u wht Wn ane sfz init footnote count reset footer trap leftover footnote de fo footer nr dn 0 zero last diver size Lif nx Ley 1 expand footnotes in evl nf retain vertical size FN footnotes rm FN delete it SEE TANAN Ey adi nr x 0 disable fx ev pop environment bp current footer place end overflow di de fx process footnote overflow if nx di fy divert overflow de fn start footnote da FN divert append footnote ev 1 in environment 1 if n x 1 fs if 1st separator fi fill mode de ef end footnote bE finish output BeZ Antiv save spacing ev pop ev di end diversion ant y n dn if nx 1 nr y a v nz uncertainty correction ch fo nyu y is negative Lif n nl l1v gt n pt ny ch fo n nlutlv didn t fit de fs separator NISDE 1 inch rule br de fz get leftover footnote Jin nt retain vertical size fy where fx put it ef nr b 1 0i bottom margin size wh 0 hd header trap wh 12i fo footer trap gt temp pos wh nbu fx fx at footer position ch fo nbu conceal fx with fo The header hd initializes a footnote count register x and sets both the current footer trap position register y and the footer trap itself to a nominal position specified in register b In addi tion if the register dn indicates a leftover foot note fz is invoked to reproce
69. vertically tall construct requiring the output line containing it to have extra vertical space before and or after it the extra line space function x N can be embedded in or attached to that word If N is negative the output line containing the word will be preceded by N extra vertical space if N is positive the output line containing the word will be followed by N extra vertical space If successive requests for extra space apply to the same line the maximum values are used The most recently utilized post line extra line space is available in the a register In x and other functions having a pair of delimiters around their parameter the delimiter choice here is arbitrary except that it can not look like the continuation of a number expression for N 5 3 Blocks of vertical space A block of vertical space is ordinarily requested using sp which honors the no space mode and which does not space past a trap A contiguous block of vertical space may be reserved using sv vs N 12pts 1 6in previous E p Set vertical baseline spacing size V Transient extra vertical space is available with x N see above ls N N 1 previous E Line spacing set to N N 1 Vs blank lines are appended to each output text line Appended blank lines are omitted if the text or previous appended blank line reached a trap position sp N N 1 V B v Space vertically in either direction If N is negative the motion is backward up
70. ward and is limited to the distance to the top of the page Forward downward motion is truncated to the distance to the nearest trap If the no space mode is on no spacing occurs see ns and rs below sv N N 1V v Save a contiguous vertical block of size N If the distance to the next trap is greater than N N vertical space is output No space mode has no effect If this distance is less than N no ver tical space is immediately output but N is remembered for later output see os Subsequent sv requests will overwrite any still remembered N OS Output saved vertical space No space mode has no effect Used to finally output a block of vertical space requested by an earlier sv request ns space D 15 No space mode turned on When on no space mode inhibits sp requests and bp requests without a next page number No space mode is turned off when a line of output occurs or with rs rs space D Restore spacing The no space mode is turned off Blank text line B Causes a break and output of a blank line exactly like sp 1 6 Line Length and Indenting The maximum line length for fill mode may be set with 11 The indent may be set with in an indent applicable to only the next output line may be set with ti The line length includes indent space but not page offset space The line length minus the indent is the basis for centering with ce The effect of 11 in or ti is delayed if a partially collected line exists un
71. x will interpolate the contents of macro xx The remainder of the line may contain up to nine arguments Strings are created by ds and appended to by as The strings x and xx are interpolated at any desired point with x and xx respectively String references and macro invocations may be nested 7 2 Copy mode input interpretation During the definition and extension of strings and macros not by diversion the input is read in copy mode In copy mode input is copied without interpretation except that e The contents of number registers indicated by n are interpolated Strings indicated by are interpolated e Arguments indicated by are interpolated e Concealed newlines indicated by newline are eliminated e Comments indicated by are eliminated t and a are interpreted as ASCII horizontal tab and SOH respectively 9 e is interpreted as 66 99 e is interpreted as These interpretations can be suppressed by prepending a For example since maps into a n will copy as n which will be interpreted as a number register indicator when the macro or string is reread 16 7 3 Arguments When a macro is invoked by name the remainder of the line is taken to contain up to nine arguments The argument separator is the space character not tab and arguments may be surrounded by double quotes to permit embedded space characters Pairs of double quotes may be embedded in double quoted

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