PostScript Error Update - Green Harbor Publications
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1. PostScript error list There are thirty possible PostScript errors See chart on the following page Some of the errors are so obscure that you are unlikely ever to see them Most have been PostScript errors since the inception of the language Some have been added with the introduction of Level 2 PostScript configurationerror invalidcontext invalidid undefinedresource and one dictfull will no longer be an error in PostScript Level 2 Dana K PostScript error configurationerror dictfull dictstackoverflow dictstactunderflow execstackoverflow handleerror interrupt invalidaccess invalidcontext invalidexit invalidfileaccess invalidfont invalidid invalidrestore ioerror limitcheck nocurrentpoint rangecheck stackoverflow stackunderflow syntaxerror timeout typecheck undefined undefinedfilename undefinedresource undefinedresult unmatchedmark unregistered VMerror The 30 kinds of PostScript errors Red Book explanation setpagedevice request cannot be satisfied no more room in dictionary too many begins too many ends exec nesting too deep called to report error information external interrupt request e g Control C attempt to violate access attribute improper use of context operation exit not in loop unacceptable access string invalid font name or dictionary invalid identifier for external object improper restore input output error occurred implementation limit exceeded2. i e an open or closing mark for example a bracket is missing occurs when there is too great a time gap between receiving two portions of the same job i e an operator expected one type of data and got something else very frequent error no definition exists in the dictionary like it says Level 2 error very obscure error often a division by zero such as a closed bracket to go with an open one undefined undocumented statusdict operator very obscure error no more available user memory Dana A PostScript error format The first two columns from the chart on page 6 are from page 359 of the PostScript Language Reference Manual Second Edition Adobe Systems Inc Addison Wesley Publishing Co Inc 1990 More information on the meaning of each error listed here is shown in the Operator Details section from page 360 553 The Additional column is drawn from a variety of sources including the PostScript Language Level 2 Reference Card see list of recommended materials explanation typical occurrence This is one more reason why lists of errors can be misleading For example new dictful errors may occur with files that have previously run without error if software applications are used together in a new fashion or even if there are releases of new versions of software So called well formed or well behaved applications those that follow the PostScript Document Struct
3. NY 11788 For subscription information on the Linotype Hell technical information series please call 1 800 842 9721 1993 Linotype Hell Company All rights reserved e Linotype and Hell are registered trademarks and LinoCheck is a trademark of Linotype Hell AG and or its subsidiaries e Adobe LaserTalk and PostScript are trademarks of Adobe Systems Inc which may be registered in certain jurisdictions e LaserCheck is a trademark of Systems of Merritt Inc All other company and product names are trademarks or registered trademarks of their respective owners Dana R
4. a fuller description see Troubleshooting PostScript Errors While Divide and Conquer is a useful technique it is also very time consuming However it requires no familiarity with PostScript programming Error handling programs are primarily helpful in finding the location of an error not in the solution But identifying the error is a very important first step towards solving the problem In addition error handling programs have other useful features For example they may print out the error on the film or save it in a location that makes it easier to find They may show you the next 2 4 lines of code or even the current point and other current page parameters Finally the most sophisticated solution to PostScript errors involves going into a file and making changes to the code Using PostScript programming in this manner is an important tool but one that requires an experienced eye and obviously some amount of programming skill LaserTalk is very useful for troubleshooting It allows you to download a file line by line and view any problems as they develop It also lets you keep track of the stacks and other parameters or current conditions during execution of a file While not strictly speaking an error handling tool analyzation programs like LinoCheck and LaserCheck allow users to identify common problems before they reach film LinoCheck is a Linotype Hell product and LaserCheck is a product developed by Systems of Merrit
5. end of this document Error types There are three possible types of errors in a PostScript environment Application and printer driver errors are commonly mentioned to Linotype Hell technical support staff Unfortunately these errors are based on lists of errors that have been compiled in the driver and they tell you very little about This topic is covered in greater the actual problem Common application and printer driver errors are 4100 detail in Troubleshooting 8133 or The job is OK but can t be printed These errors do not help very PostScript Errors which appears much in troubleshooting in the 1992 Linotype Hell technical information notebook RIP reported errors are the errors that appear on the panel of a Raster Image Processor RIP or imagesetter Probably the most common Linotype Hell RIP error is E12 no take up cassette These errors are listed in the RIP user manual and are usually very easily solved PostScript interpreter errors are reported back from the RIP after a job has been processed Finding these errors is the first step in troubleshooting Application and printer driver errors may be intertwined with PostScript interpreter errors in the following fashion Sometimes the actual PostScript interpreter error is intercepted by the driver and replaced with an application or printer driver error The PostScript interpreter error may appear on the screen only very briefly or may be thrown away entirely
6. Linotype Hell Technical PostScript Information Error Update Technical support personnel at Linotype Hell are asked many questions related to the PostScript page description language but undoubtedly the most common request that they get is for lists of PostScript errors To that end reprinted in this article is a list of PostScript errors from Adobe Systems Red book The PostScript Language Reference Manual Addison Wesley But there is much more to troubleshooting than lists of errors and solutions If lists were the only thing required for troubleshooting then PostScript errors would be easily solved in every case In fact cause solution lists can often be deceptive rather than helpful Why Because a given error may have many possible causes and any list that is created is locked in time based on the PostScript version the software application version hardware revisions and many other variables As technology changes the list is soon outmoded It is more important to teach people how to approach PostScript error troubleshooting That was the purpose of the article Troubleshooting PostScript Errors which is included in the 1992 Linotype Hell technical information notebook Still there is no way of getting around the fact that the most advanced troubleshooting methods require that the troubleshooter have some familiarity with PostScript programming For that reason a number of PostScript programming resources are listed at the
7. current point is undefined operand out of bounds operand stack overflow operand stack underflow PostScript language syntax error time limit exceeded operand of wrong type name not known file not found resource instance not found over underflow or meaningless result expected mark not on stack internal error VM exhausted Additional explanation typical occurrence i e a requested feature that is not available on that device see description on page 7 each begin command must have a corresponding end command each end command must have a corresponding begin command too many pending nested procedure calls very obscure error not actually an error procedure Control C is used to abort a program i e writing to a read only dictionary Display PostScript error exit command improperly used very obscure error i e writing to a read only file very obscure error corrupted or improperly formed font dictionary Display PostScript error often a string dictionary or procedure is left on the stack that needs to be discarded before restore may signal incorrect handshaking protocol or improperly terminated or faulty cables i e with too many path elements in a lineto or curveto segment i e if the required moveto command is not supplied i e a film width request greater than that used by the target output device received more data than it can accommodate expected more data than it received
8. ften occur because the target dictionary is not on the top of the dictionary stack If the same key occurs in two dictionaries the RIP will take the first occurrence of the key that it finds and that may not be the one that was redefined The dictfull error is a good example of how changes in the PostScript page description language change the nature of the errors that users see Engineers at Adobe Systems concerned by problems with dictionaries with fixed limits decided to integrate a method of increasing dictionary size on the fly into PostScript Level 2 By increasing the size of a dictionary as it starts to fill up dictfull errors can be avoided This is one of many changes that have been made in PostScript Level 2 and is the reason why dictfull errors will not appear in PostScript Level 2 devices Troubleshooting is the process of finding out what the error is and then once the error is known doing something about it There are a number of different levels of complexity in troubleshooting some requiring diagnostic tools or programming experience and some being quite simple Dana 7 Adobe Systems Inc the maker of LaserTalk is in the process of producing an updated version Analyzation programs Conclusion Recommended maiterials Acknowledgements Divide and Conquer is a simple strategy that narrows down the location of a PostScript error by removing or simplifying page elements until the job prints error free For
9. or because the interpreter is usually in the process of defining something when it discovers that there is no more room in the dictionary The dictfull error is very common and often occurs because of problems related to the software application e The software application may create too small a dictionary and then proceed to create to many entries for that dictionary Or other applications may use the dictionary in ways that the first software application programmers didn t anticipate The software application may use an existing dictionary in most cases the userdict The userdict is a device dependent dictionary containing spaces for 200 entries The number of entries actually used will vary with different output devices and PS versions This is one common reason why files that run on a laser printer may not run to a high resolution output device the laser printer s userdict may be nearly empty and is not overtaxed by applications that use it The situation is very different in the userdicts of more sophisticated output devices Certain keys have to be placed in the userdict by the raster image processor RIP running the imagesetter This leaves fewer available spots in these userdicts for a software application that might choose to use it Because there are a number of different dictionaries that may be placed on the dictionary stack there may be some problem when a PostScript program adds to its dictionary For example errors o
10. t see below These are the two most important troubleshooting tips e Learn to identify the PostScript error Having the real error message rather than an application or printer driver message makes it easier to proceed with troubleshooting e Learn more about the PostScript page description language Here are some good sources of information on PostScript programming e Two books by Glenn Reid provide excellent and very readable information on PostScript They are Thinking in PostScript and PostScript Language Program Design also known as the Green book Both books are published by Addison Wesley e Frank Braswell of Systems of Merritt has produced a handy plastic coated one page reference sheet of PostScript operators interpreter messages and errors This is a nice tool for the serious troubleshooter Braswell also offers a two day seminar on PostScript error troubleshooting call him at 205 660 1240 for more information e Acquired Knowledge offers a variety of classes on PostScript programming call them at 619 587 4668 for more information Many thanks to Frank Braswell of Systems of Merritt Bob Schaffel executive director of the Professional Prepress Alliance and Gus Barbuto of Linotype Hell Company for their help in producing this document Please direct any questions or comments to February 1993 Part Number 7006 Jim Hamilton Marketing Department Linotype Hell Company 425 Oser Avenue Hauppauge
11. uring Conventions should not cause this kind of problem but in the real world not all applications are well formed 8A stack is a holding place for all different types of data There are several stacks that are used in PostScript including one for dictionaries Troubleshooting The format of PostScript errors from the RIP always consists of two parts the type of error and the offending command Any other message formats are generated either by the application or printer driver The message coming back from the RIP will usually look like this o rod le Error OffendingCommand 3 Here s an example 6 Error dictfull OffendingCommand def In the above example the type of error is dictfull and defis the offending command Generally a dictfull error occurs when the PostScript program attempts to define a new entry in a dictionary that is already full A dictionary has a fixed limit on the number of entries that it can hold and this limit is established when the dictionary is created Dictionaries are created to hold pairs of PostScript objects for example a variable and its current value The offending command is the command that was being executed when the error occurred In this example the def operator tells the interpreter to define a name called a key and associate it with a value which can be a number a procedure or even a dictionary The def command almost always appears with a dictfull err
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