This is Info file eplain.info, produced by Makeinfo-1.55 from the input file eplain.texi. This file documents the Eplain macros. Copyright (C) 1989, 90, 91, 92, 93, 94 Karl Berry. Steven Smith wrote the documentation for the commutative diagram macros. (He also wrote the macros.) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the section entitled "GNU General Public License" is included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the section entitled "GNU General Public License" may be included in a translation approved by the author instead of in the original English. File: eplain.info, Node: Allocation macros, Next: Iteration, Prev: Category codes, Up: Programming definitions Allocation macros ================= Plain TeX provides macros that allocate registers of each primitive type in TeX, to prevent different sets of macros from using the same register for two different things. The macros are all named starting with `new', e.g., `\newcount' allocates a new "count" (integer) register. Such allocations are usually needed only at the top level of some macro definition file; therefore, plain TeX makes the allocation registers `\outer', to help find errors. (The error this helps to find is a missing right brace in some macro definition.) Sometimes, however, it is useful to allocate a register as part of some macro. An outer control sequence cannot be used as part of a macro definition (or in a few other contexts: the parameter text of a definition, an argument to a definition, the preamble of an alignment, or in conditional text that is being skipped). Therefore, Eplain defines "inner" versions of all the allocation macros, named with the prefix `inner': `\innernewbox', `\innernewcount', `\innernewdimen', `\innernewfam', `\innernewhelp', `\innernewif', `\innernewinsert', `\innernewlanguage', `\innernewread', `\innernewskip', `\innernewtoks', `\innernewwrite'. You can also define non-outer versions of other macros in the same way that Eplain defines the above. The basic macro is called `\innerdef': \innerdef \INNERNAME {OUTERNAME} The first argument (\INNERNAME) to `\innerdef' is the control sequence that you want to define. Any previous definition of \INNERNAME is replaced. The second argument (OUTERNAME) is the *characters* in the name of the outer control sequence. (You can't use the actual control sequence name, since it's outer!) If the outer control sequence is named \CS, and you want to define `innerCS' as the inner one, you can use `\innerinnerdef', which is just an abbreviation for a call to `\innerdef'. For example, these two calls are equivalent: \innerdef\innerproclaim{proclaim} \innerinnerdef{proclaim} File: eplain.info, Node: Iteration, Next: Macro arguments, Prev: Allocation macros, Up: Programming definitions Iteration ========= You can iterate through a comma-separated list of items with `\for'. Here is an example: \for\name:=karl,kathy\do{% \message{\name}% }% This writes `karl' and `kathy' to the terminal. Spaces before or after the commas in the list, or after the `:=', are *not* ignored. `\for' expands the iterated values fully (with `\edef'), so this is equivalent to the above: \def\namelist{karl,kathy}% \for\name:=\namelist\do ... File: eplain.info, Node: Macro arguments, Next: Converting to characters, Prev: Iteration, Up: Programming definitions Macro arguments =============== It is occasionally useful to redefine a macro that takes arguments to do nothing. Eplain defines `\gobble', `\gobbletwo', and `\gobblethree' to swallow one, two, and three arguments, respectively. For example, if you want to produce a "short" table of contents--one that includes only chapters, say--the easiest thing to do is read the entire `.toc' file (*note Contents::.), and just ignore the commands that produce section or subsection entries. To be specific: \let\tocchapterentry = \shorttocchapter \let\tocsectionentry = \gobbletwo \let\tocsubsectionentry = \gobbletwo \readtocfile (Of course, this assumes you only have chapters, sections, and subsections in your document.) In addition, Eplain defines `\eattoken' to swallow the single following token, using `\let'. Thus, `\gobble' followed by `{...}' ignores the entire brace-enclosed text. `\eattoken' followed by the same ignores only the opening left brace. Eplain defines a macro `\identity' which takes one argument and expands to that argument. This may be useful if you want to provide a function for the user to redefine, but don't need to do anything by default. (For example, the default definition of `\eqconstruct' (*note Formatting equation references::.) is `\identity'.) You may also want to read an optional argument. The established convention is that optional arguments are put in square brackets, so that is the syntax Eplain recognizes. Eplain ignores space tokens before an optional argument, via `\futurenonspacelet'. You test for an optional argument by using `\@getoptionalarg'. It takes one argument, a control sequence to expand after reading the argument, if present. If an optional argument is present, the control sequence `\@optionalarg' expands to it; otherwise, `\@optionalarg' is `\empty'. You must therefore have the category code of `@' set to 11 (letter). Here is an example: \catcode`@=\letter \def\cmd{\@getoptionalarg\finishcmd} \def\finishcmd{% \ifx\@optionalarg\empty % No optional argument present. \else % One was present. \fi } If an optional argument contains another optional argument, the inner one will need to be enclosed in braces, so TeX does not mistake the end of the first for the end of the second. File: eplain.info, Node: Converting to characters, Next: Expansion, Prev: Macro arguments, Up: Programming definitions Converting to characters ======================== Eplain defines `\xrlabel' to produce control sequence names for cross-reference labels, et al. This macro expands to its argument with an `_' appended. (It does this because the usual use of `\xrlabel' is to generate a control sequence name, and we naturally want to avoid conflicts between control sequence names.) Because `\xrlabel' is fully expandable, to make a control sequence name out of the result you need only do `\csname \xrlabel{LABEL}\endcsname' The `\csname' primitive makes a control sequence name out of any sequence of character tokens, regardless of category code. Labels can therefore include any characters except for `\', `{', `}', and `#', all of which are used in macro definitions themselves. `\sanitize' takes a control sequence as an argument and converts the expansion of the control sequence into a list of character tokens. This is the behavior you want when writing information like chapter titles to an output file. For example, here is part of the definition of `\writenumberedtocentry'; `#2' is the title that the user has given. ... \def\temp{#2}% ... \write\tocfile{% ... \sanitize\temp ... }% File: eplain.info, Node: Expansion, Next: Obeying spaces, Prev: Converting to characters, Up: Programming definitions Expansion ========= This section describes some miscellanous macros for expansion, etc. * Menu: * \csn and \ece:: Abbreviations for \csname expansions. * \edefappend:: * Hooks:: Manipulating and executing named actions. * Properties:: Associating information with a csname. * \expandonce:: * \ifundefined:: * \futurenonspacelet:: File: eplain.info, Node: \csn and \ece, Next: \edefappend, Up: Expansion `\csn' and `\ece' ----------------- `\csn'{NAME} simply abbreviates `\csname' NAME `\encsname', thus saving some typing. The extra level of expansion does take some time, though, so I don't recommend it for an inner loop. `\ece'{TOKEN}{NAME} abbreviates \expandafter TOKEN \csname NAME \endcsname For example, \def\fontabbrevdef#1#2{\ece\def{@#1font}{#2}} \fontabbrevdef{normal}{ptmr} defines a control sequence `\@normalfont' to expand to `ptmr'. File: eplain.info, Node: \edefappend, Next: Hooks, Prev: \csn and \ece, Up: Expansion `\edefappend' ------------- `\edefappend' is a way of adding on to an existing definition. It takes two arguments: the first is the control sequence name, the second the new tokens to append to the definition. The second argument is fully expanded (in the `\edef' that redefines the control sequence). For example: \def\foo{abc} \def\bar{xyz} \edefappend\foo{\bar karl} results in `\foo' being defined as `abcxyzkarl'. File: eplain.info, Node: Hooks, Next: Properties, Prev: \edefappend, Up: Expansion Hooks ----- A "hook" is simply a name for a group of actions which is executed in certain places--presumably when it is most useful to allow customization or modification. TeX already provides many builtin hooks; for example, the `\every ...' token lists are all examples of hooks. Eplain provides several macros for adding actions to hooks. They all take two arguments: the name of the hook and the new actions. `hookaction NAME ACTIONS' `hookappend NAME ACTIONS' `hookprepend NAME ACTIONS' Each of these adds ACTIONS to the hook NAME. (Any previously-defined actions are retained.) NAME is not a control sequence, but rather the characters of the name. `hookactiononce NAME `\CS'' `\hookactiononce' adds CS to NAME, like the macros above, but first it adds \global\let \CS \relax to the definition of \CS. (This implies \CS must be a true expandable macro, not a control sequence `\let' to a primitive or some other such thing.) Thus, \CS is expanded the next time the hook NAME is run, but it will disappear after that. The `\global' is useful because `\hookactiononce' is most useful when the grouping structure of the TeX code could be anything. Neither this nor the other hook macros do global assignments to the hook variable itself, so TeX's usual grouping rules apply. The companion macro to defining hook actions is `\hookrun', for running them. This takes a single argument, the name of the hook. If no actions for the hook are defined, no error ensues. Here is a skeleton of general `\begin' and `\end' macros that run hooks, and a couple of calls to define actions. The use of `\hookprepend' for the begin action and `\hookappend' for the end action ensures that the actions are executed in proper sequence with other actions (as long as the other actions use `\hookprepend' and `\hookappend' also). \def\begin#1{ ... \hookrun{begin} ... } \def\end#1{ ... \hookrun{end} ... } \hookprepend{begin}\start_underline \hookappend{end}\finish_underline File: eplain.info, Node: Properties, Next: \expandonce, Prev: Hooks, Up: Expansion Properties ---------- A "property" is a name/value pair associated with another symbol, traditionally called an "atom". Both atom and property names are control sequence names. Eplain provides two macros for dealing with property lists: `\setproperty' and `\getproperty'. `\setproperty ATOM PROPNAME VALUE' `\setproperty' defines the property PROPERTY on the atom ATOM to be VALUE. ATOM and PROPNAME can be anything acceptable to `\csname'. VALUE can be anything. `\getproperty ATOM PROPNAME' `\getproperty' expands to the value stored for PROPNAME on ATOM. If PROPNAME is undefined, it expands to nothing (i.e., `\empty'). The idea of properties originated in Lisp (I believe). There, the implementation truly does associate properties with atoms. In TeX, where we have no builtin support for properties, the association is only conceptual. The following example typesets `xyz'. \setproperty{a}{pr}{xyz} \getproperty{a}{pr} File: eplain.info, Node: \expandonce, Next: \ifundefined, Prev: Properties, Up: Expansion `\expandonce' ------------- `\expandonce' is defined as `\expandafter\noexpand'. Thus, `\expandonce TOKEN' expands TOKEN once, instead of to TeX primitives. This is most useful in an `\edef'. For example, the following defines `\temp' to be `\foo', not `abc'. \def\foo{abc} \def\bar{\foo} \edef\temp{\expandonce\bar} File: eplain.info, Node: \ifundefined, Next: \futurenonspacelet, Prev: \expandonce, Up: Expansion `\ifundefined' -------------- `\ifundefined{CS} T \else F \fi' expands the T text if the control sequence `\CS' is undefined or has been `\let' to `\relax', and the F text otherwise. Since `\ifundefined' is not a primitive conditional, it cannot be used in places where TeX might skip tokens "at high speed", e.g., within another conditional--TeX can't match up the `\if''s and `\fi''s. This macro was taken directly from `The TeXbook', page 308. File: eplain.info, Node: \futurenonspacelet, Prev: \ifundefined, Up: Expansion `\futurenonspacelet' -------------------- The `\futurelet' primitive allows you to look at the next token from the input. Sometimes, though, you want to look ahead ignoring any spaces. This is what `\futurenonspacelet' does. It is otherwise the same as `\futurelet': you give it two control sequences as arguments, and it assigns the next nonspace token to the first, and then expands the second. For example: \futurenonspacelet\temp\finishup \def\finishup{\ifx\temp ...} File: eplain.info, Node: Obeying spaces, Next: Writing out numbers, Prev: Expansion, Up: Programming definitions Obeying spaces ============== `\obeywhitespace' makes both end-of-lines and space characters in the input be respected in the output. Unlike plain TeX's `\obeyspaces', even spaces at the beginnings of lines turn into blank space. By default, the size of the space that is produced by a space character is the natural space of the current font, i.e., what `\ ' produces. Ordinarily, a blank line in the input produces as much blank vertical space as a line of text would occupy. You can adjust this by assigning to the parameter `\blanklineskipamount': if you set this negative, the space produced by a blank line will be smaller; if positive, larger. Tabs are not affected by this routine. In particular, if tabs occur at the beginning of a line, they will disappear. (If you are trying to make TeX do the "right thing" with tabs, don't. Use a utility program like expand instead.) File: eplain.info, Node: Writing out numbers, Next: Mode-specific penalties, Prev: Obeying spaces, Up: Programming definitions Writing out numbers =================== `\numbername' produces the written-out form of its argument, i.e., `zero' through `ten' for the numbers 0-10, and numerals for all others. File: eplain.info, Node: Mode-specific penalties, Next: Auxiliary files, Prev: Writing out numbers, Up: Programming definitions Mode-specific penalties ======================= TeX's built-in `\penalty' command simply appends to the current list, no matter what kind of list it is. You might intend a particular penalty to always be a "vertical" penalty, however, i.e., appended to a vertical list. Therefore, Eplain provides `\vpenalty' and `\hpenalty' which first leave the other mode and then do `\penalty'. More precisely, `\vpenalty' inserts `\par' if the current mode is horizontal, and `\hpenalty' inserts `\leavevmode' if the current mode is vertical. (Thus, `\vpenalty' cannot be used in math mode.) File: eplain.info, Node: Auxiliary files, Prev: Mode-specific penalties, Up: Programming definitions Auxiliary files =============== It is common to write some information out to a file to be used on a subsequent run. But when it is time to read the file again, you only want to do so if the file actually exists. `\testfileexistence' is given an argument which is appended to `\jobname', and sets the conditional `\iffileexists' appropriately. For example: \testfileexistence{toc}% \iffileexists \input \jobname.toc \fi File: eplain.info, Node: Copying, Next: Freedom, Prev: Programming definitions, Up: Top GNU GENERAL PUBLIC LICENSE ************************** Version 2, June 1991 Copyright (C) 1989, 1991 Free Software Foundation, Inc. 675 Mass Ave, Cambridge, MA 02139, USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble ======== The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too. When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things. To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it. For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights. We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software. Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations. Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all. The precise terms and conditions for copying, distribution and modification follow. TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 1. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term "modification".) Each licensee is addressed as "you". Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does. 2. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program. You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee. 3. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions: a. You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change. b. You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License. c. If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.) These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it. Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program. In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License. 4. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following: a. Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, b. Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, c. Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.) The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable. If distribution of executable or object code is made by offering access to copy from a designated place, then offering equivalent access to copy the source code from the same place counts as distribution of the source code, even though third parties are not compelled to copy the source along with the object code. 5. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance. 6. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it. 7. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients' exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License. 8. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program. If any portion of this section is held invalid or unenforceable under any particular circumstance, the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances. It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices. Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice. This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License. 9. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License. 10. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and "any later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation. 11. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally. NO WARRANTY 12. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 13. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. END OF TERMS AND CONDITIONS Appendix: How to Apply These Terms to Your New Programs ======================================================= If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms. To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found. ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES. Copyright (C) 19YY NAME OF AUTHOR This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. Also add information on how to contact you by electronic and paper mail. If the program is interactive, make it output a short notice like this when it starts in an interactive mode: Gnomovision version 69, Copyright (C) 19YY NAME OF AUTHOR Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details. The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than `show w' and `show c'; they could even be mouse-clicks or menu items--whatever suits your program. You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the program, if necessary. Here is a sample; alter the names: Yoyodyne, Inc., hereby disclaims all copyright interest in the program `Gnomovision' (which makes passes at compilers) written by James Hacker. SIGNATURE OF TY COON, 1 April 1989 Ty Coon, President of Vice This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Library General Public License instead of this License. File: eplain.info, Node: Freedom, Next: Macro index, Prev: Copying, Up: Top Regain your programming freedom ******************************* Until a few years ago, programmers in the United States could write any program they wished. This freedom has now been taken away by two developments: software patents, which grant the patent holder an absolute monopoly on some programming technique, and user interface copyright, which forbid compatible implementations of an existing user interface. In Europe, especially through the GATT treaty, things are rapidly approaching the same pass. * Menu: * Software patents:: Algorithm monopolies. * User interface copyright:: Forbidding upward-compatibility. * What to do?:: What to do? File: eplain.info, Node: Software patents, Next: User interface copyright, Up: Freedom Software patents ================ The U.S. Patent and Trademark Office has granted numerous software patents on software techniques. Patents are an absolute monopoly--independent reinvention is precluded. This monopoly lasts for seventeen years, i.e., forever (with respect to computer science). One patent relevant to TeX is patent 4,956,809, issued to the Mark Williams company on September 11, 1990, applied for in 1982, which covers (among other things) representing in a standardized order consisting of a standard binary structure file stored on auxiliary memory or transported on a communications means, said standardized order being different from a different order used on at least one of the different computers; Converting in each of the different computers binary data read from an auxiliary data storage or communications means from the standardized order to the natural order of the respective host computer after said binary data are read from said auxiliary data storage or communications means and before said binary data are used by the respective host computer; and Converting in each of the different computers binary data written into auxiliary data storage or communications means from the natural order of the respective host computer to the standardized order prior to said writing. ... in other words, storing data on disk in a machine-independent order, as the DVI, TFM, GF, and PK file formats specify. Even though TeX is "prior art" in this respect, the patent was granted (the patent examiners not being computer scientists, even less computer typographers). Since there is a strong presumption in the courts of a patent's validity once it has been granted, there is a good chance that users or implementors of TeX could be successfully sued on the issue. As another example, the X window system, which was intended to be able to be used freely by everyone, is now being threatened by two patents: 4,197,590 on the use of exclusive-or to redraw cursors, held by Cadtrak, a litigation company (this has been upheld twice in court); and 4,555,775, held by AT&T, on the use of backing store to redraw windows quickly. Here is one excerpt from a recent mailing by the League for Programming Freedom (*note What to do?::.) which I feel sums up the situation rather well. It comes from an article in `Think' magazine, issue #5, 1990. The comments after the quote were written by Richard Stallman. "You get value from patents in two ways," says Roger Smith, IBM Assistant General Counsel, intellectual property law. "Through fees, and through licensing negotiations that give IBM access to other patents. "The IBM patent portfolio gains us the freedom to do what we need to do through cross-licensing--it gives us access to the inventions of others that are the key to rapid innovation. Access is far more valuable to IBM than the fees it receives from its 9,000 active patents. There's no direct calculation of this value, but it's many times larger than the fee income, perhaps an order of magnitude larger." This information should dispel the belief that the patent system will "protect" a small software developer from competition from IBM. IBM can always find patents in its collection which the small developer is infringing, and thus obtain a cross-license. However, the patent system does cause trouble for the smaller companies which, like IBM, need access to patented techniques in order to do useful work in software. Unlike IBM, the smaller companies do not have 9,000 patents and cannot usually get a cross-license. No matter how hard they try, they cannot have enough patents to do this. Only the elimination of patents from the software field can enable most software developers to continue with their work. The value IBM gets from cross-licensing is a measure of the amount of harm that the patent system would do to IBM if IBM could not avoid it. IBM's estimate is that the trouble could easily be ten times the good one can expect from one's own patents--even for a company with 9,000 of them. File: eplain.info, Node: User interface copyright, Next: What to do?, Prev: Software patents, Up: Freedom User interface copyright ======================== (This section is copied from the GCC manual, by Richard Stallman.) This section is a political message from the League for Programming Freedom to the users of the GNU font utilities. It is included here as an expression of support for the League on my part. Apple, Lotus and Xerox are trying to create a new form of legal monopoly: a copyright on a class of user interfaces. These monopolies would cause serious problems for users and developers of computer software and systems. Until a few years ago, the law seemed clear: no one could restrict others from using a user interface; programmers were free to implement any interface they chose. Imitating interfaces, sometimes with changes, was standard practice in the computer field. The interfaces we know evolved gradually in this way; for example, the Macintosh user interface drew ideas from the Xerox interface, which in turn drew on work done at Stanford and SRI. 1-2-3 imitated VisiCalc, and dBase imitated a database program from JPL. Most computer companies, and nearly all computer users, were happy with this state of affairs. The companies that are suing say it does not offer "enough incentive" to develop their products, but they must have considered it "enough" when they made their decision to do so. It seems they are not satisfied with the opportunity to continue to compete in the marketplace--not even with a head start. If Xerox, Lotus, and Apple are permitted to make law through the courts, the precedent will hobble the software industry: * Gratuitous incompatibilities will burden users. Imagine if each car manufacturer had to arrange the pedals in a different order. * Software will become and remain more expensive. Users will be "locked in" to proprietary interfaces, for which there is no real competition. * Large companies have an unfair advantage wherever lawsuits become commonplace. Since they can easily afford to sue, they can intimidate small companies with threats even when they don't really have a case. * User interface improvements will come slower, since incremental evolution through creative imitation will no longer be permitted. * Even Apple, etc., will find it harder to make improvements if they can no longer adapt the good ideas that others introduce, for fear of weakening their own legal positions. Some users suggest that this stagnation may already have started. * If you use GNU software, you might find it of some concern that user interface copyright will make it hard for the Free Software Foundation to develop programs compatible with the interfaces that you already know. File: eplain.info, Node: What to do?, Prev: User interface copyright, Up: Freedom What to do? =========== (This section is copied from the GCC manual, by Richard Stallman.) To protect our freedom from lawsuits like these, a group of programmers and users have formed a new grass-roots political organization, the League for Programming Freedom. The purpose of the League is to oppose new monopolistic practices such as user-interface copyright and software patents; it calls for a return to the legal policies of the recent past, in which these practices were not allowed. The League is not concerned with free software as an issue, and not affiliated with the Free Software Foundation. The League's membership rolls include John McCarthy, inventor of Lisp, Marvin Minsky, founder of the Artificial Intelligence lab, Guy L. Steele, Jr., author of well-known books on Lisp and C, as well as Richard Stallman, the developer of GNU CC. Please join and add your name to the list. Membership dues in the League are $42 per year for programmers, managers and professionals; $10.50 for students; $21 for others. The League needs both activist members and members who only pay their dues. To join, or for more information, phone (617) 492-0023 or write to: League for Programming Freedom 1 Kendall Square #143 P.O. Box 9171 Cambridge, MA 02139 You can also send electronic mail to `league@prep.ai.mit.edu'. Here are some suggestions from the League for things you can do to protect your freedom to write programs: * Don't buy from Xerox, Lotus or Apple. Buy from their competitors or from the defendants they are suing. * Don't develop software to work with the systems made by these companies. * Port your existing software to competing systems, so that you encourage users to switch. * Write letters to company presidents to let them know their conduct is unacceptable. * Tell your friends and colleagues about this issue and how it threatens to ruin the computer industry. * Above all, don't work for the look-and-feel plaintiffs, and don't accept contracts from them. * Write to Congress to explain the importance of this issue. House Subcommittee on Intellectual Property 2137 Rayburn Bldg Washington, DC 20515 Senate Subcommittee on Patents, Trademarks and Copyrights United States Senate Washington, DC 20510 (These committees have received lots of mail already; let's give them even more.) Express your opinion! You can make a difference.