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* gasp: (gasp). The GNU Assembler Preprocessor
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File:, Node: Top, Next: Overview, Up: (dir)
GASP is a preprocessor for assembly programs.
This file describes version 1 of GASP.
Steve Chamberlain wrote GASP; Roland Pesch wrote this manual.
* Menu:
* Overview:: What is GASP?
* Invoking GASP:: Command line options.
* Commands:: Preprocessor commands.
* GNU Free Documentation License:: GNU Free Documentation License
* Index:: Index.

File:, Node: Overview, Next: Invoking GASP, Prev: Top, Up: Top
What is GASP?
The primary purpose of the GNU assembler is to assemble the output of
other programs--notably compilers. When you have to hand-code
specialized routines in assembly, that means the GNU assembler is an
unfriendly processor: it has no directives for macros, conditionals, or
many other conveniences that you might expect.
In some cases you can simply use the C preprocessor, or a generalized
preprocessor like M4; but this can be awkward, since none of these
things are designed with assembly in mind.
GASP fills this need. It is expressly designed to provide the
facilities you need with hand-coded assembly code. Implementing it as a
preprocessor, rather than part of the assembler, allows the maximum
flexibility: you can use it with hand-coded assembly, without paying a
penalty of added complexity in the assembler you use for compiler
Here is a small example to give the flavor of GASP. This input to
.MACRO saveregs from=8 to=14
count .ASSIGNA \from
! save r\from..r\to
.AWHILE \&count LE \to
mov r\&count,@-sp
count .ASSIGNA \&count + 1
saveregs from=12
bar: mov #H'dead+10,r0
foo .SDATAC "hello"<10>
generates this assembly program:
! save r12..r14
mov r12,@-sp
mov r13,@-sp
mov r14,@-sp
bar: mov #57005+10,r0
foo: .byte 6,104,101,108,108,111,10

File:, Node: Invoking GASP, Next: Commands, Prev: Overview, Up: Top
Command Line Options
The simplest way to use GASP is to run it as a filter and assemble
its output. In Unix and its ilk, you can do this, for example:
$ gasp prog.asm | as -o prog.o
Naturally, there are also a few command-line options to allow you to
request variations on this basic theme. Here is the full set of
possibilities for the GASP command line.
gasp [ -a | --alternate ]
[ -c CHAR | --commentchar CHAR ]
[ -d | --debug ] [ -h | --help ] [ -M | --mri ]
[ -o OUTFILE | --output OUTFILE ]
[ -p | --print ] [ -s | --copysource ]
[ -u | --unreasonable ] [ -v | --version ]
`INFILE ...'
The input file names. You must specify at least one input file;
if you specify more, GASP preprocesses them all, concatenating the
output in the order you list the INFILE arguments.
Mark the end of each input file with the preprocessor command
`.END'. *Note Miscellaneous commands: Other Commands.
Use alternative macro syntax. *Note Alternate macro syntax:
Alternate, for a discussion of how this syntax differs from the
default GASP syntax.
`-c 'CHAR''
`--commentchar 'CHAR''
Use CHAR as the comment character. The default comment character
is `!'. For example, to use a semicolon as the comment character,
specify `-c ';'' on the GASP command line. Since assembler
command characters often have special significance to command
shells, it is a good idea to quote or escape CHAR when you specify
a comment character.
For the sake of simplicity, all examples in this manual use the
default comment character `!'.
Show debugging statistics. In this version of GASP, this option
produces statistics about the string buffers that GASP allocates
internally. For each defined buffersize S, GASP shows the number
of strings N that it allocated, with a line like this:
strings size S : N
GASP displays these statistics on the standard error stream, when
done preprocessing.
Display a summary of the GASP command line options.
Use MRI compatibility mode. Using this option causes GASP to
accept the syntax and pseudo-ops used by the Microtec Research
`ASM68K' assembler.
`--output OUTFILE'
Write the output in a file called OUTFILE. If you do not use the
`-o' option, GASP writes its output on the standard output stream.
Print line numbers. GASP obeys this option _only_ if you also
specify `-s' to copy source lines to its output. With `-s -p',
GASP displays the line number of each source line copied
(immediately after the comment character at the beginning of the
Copy the source lines to the output file. Use this option to see
the effect of each preprocessor line on the GASP output. GASP
places a comment character (`!' by default) at the beginning of
each source line it copies, so that you can use this option and
still assemble the result.
Bypass "unreasonable expansion" limit. Since you can define GASP
macros inside other macro definitions, the preprocessor normally
includes a sanity check. If your program requires more than 1,000
nested expansions, GASP normally exits with an error message. Use
this option to turn off this check, allowing unlimited nested
Display the GASP version number.

File:, Node: Commands, Next: GNU Free Documentation License, Prev: Invoking GASP, Up: Top
Preprocessor Commands
GASP commands have a straightforward syntax that fits in well with
assembly conventions. In general, a command extends for a line, and may
have up to three fields: an optional label, the command itself, and
optional arguments to the command. You can write commands in upper or
lower case, though this manual shows them in upper case. *Note Details
of the GASP syntax: Syntax Details, for more information.
* Menu:
* Conditionals::
* Loops::
* Variables::
* Macros::
* Data::
* Listings::
* Other Commands::
* Syntax Details::
* Alternate::

File:, Node: Conditionals, Next: Loops, Up: Commands
Conditional assembly
The conditional-assembly directives allow you to include or exclude
portions of an assembly depending on how a pair of expressions, or a
pair of strings, compare.
The overall structure of conditionals is familiar from many other
contexts. `.AIF' marks the start of a conditional, and precedes
assembly for the case when the condition is true. An optional
`.AELSE' precedes assembly for the converse case, and an `.AENDI' marks
the end of the condition.
You may nest conditionals up to a depth of 100; GASP rejects nesting
beyond that, because it may indicate a bug in your macro structure.
Conditionals are primarily useful inside macro definitions, where you
often need different effects depending on argument values. *Note
Defining your own directives: Macros, for details about defining macros.
The governing condition goes on the same line as the `.AIF'
preprocessor command. You may compare either two strings, or two
When you compare strings, only two conditional CMP comparison
operators are available: `EQ' (true if STRA and STRB are
identical), and `NE' (the opposite).
When you compare two expressions, _both expressions must be
absolute_ (*note Arithmetic expressions in GASP: Expressions.).
You can use these CMP comparison operators with expressions:
Are EXPRA and EXPRB equal? (For strings, are STRA and STRB
Are EXPRA and EXPRB different? (For strings, are STRA and
STRB different?
Is EXPRA less than EXPRB? (Not allowed for strings.)
Is EXPRA less than or equal to EXPRB? (Not allowed for
Is EXPRA greater than EXPRB? (Not allowed for strings.)
Is EXPRA greater than or equal to EXPRB? (Not allowed for
Marks the start of assembly code to be included if the condition
fails. Optional, and only allowed within a conditional (between
`.AIF' and `.AENDI').
Marks the end of a conditional assembly.

File:, Node: Loops, Next: Variables, Prev: Conditionals, Up: Commands
Repetitive sections of assembly
Two preprocessor directives allow you to repeatedly issue copies of
the same block of assembly code.
If you simply need to repeat the same block of assembly over and
over a fixed number of times, sandwich one instance of the
repeated block between `.AREPEAT' and `.AENDR'. Specify the
number of copies as AEXP (which must be an absolute expression).
For example, this repeats two assembly statements three times in
rotcl r2
div1 r0,r1
To repeat a block of assembly depending on a conditional test,
rather than repeating it for a specific number of times, use
`.AWHILE'. `.AENDW' marks the end of the repeated block. The
conditional comparison works exactly the same way as for `.AIF',
with the same comparison operators (*note Conditional assembly:
Since the terms of the comparison must be absolute expression,
`.AWHILE' is primarily useful within macros. *Note Defining your
own directives: Macros.
You can use the `.EXITM' preprocessor directive to break out of
loops early (as well as to break out of macros). *Note Defining your
own directives: Macros.

File:, Node: Variables, Next: Macros, Prev: Loops, Up: Commands
Preprocessor variables
You can use variables in GASP to represent strings, registers, or
the results of expressions.
You must distinguish two kinds of variables:
1. Variables defined with `.EQU' or `.ASSIGN'. To evaluate this kind
of variable in your assembly output, simply mention its name. For
example, these two lines define and use a variable `eg':
eg .EQU FLIP-64
mov.l eg,r0
_Do not use_ this kind of variable in conditional expressions or
while loops; GASP only evaluates these variables when writing
assembly output.
2. Variables for use during preprocessing. You can define these with
`.ASSIGNC' or `.ASSIGNA'. To evaluate this kind of variable,
write `\&' before the variable name; for example,
opcit .ASSIGNA 47
.AWHILE \&opcit GT 0
GASP treats macro arguments almost the same way, but to evaluate
them you use the prefix `\' rather than `\&'. *Note Defining your
own directives: Macros.
Assign preprocessor variable PVAR the value of the expression
EXPR. There are no restrictions on redefinition; use `.EQU' with
the same PVAR as often as you find it convenient.
Almost the same as `.EQU', save that you may not redefine PVAR
using `.ASSIGN' once it has a value.
Define a variable with a numeric value, for use during
preprocessing. AEXPR must be an absolute expression. You can
redefine variables with `.ASSIGNA' at any time.
Define a variable with a string value, for use during
preprocessing. You can redefine variables with `.ASSIGNC' at any
Use `.REG' to define a variable that represents a register. In
particular, REGISTER is _not evaluated_ as an expression. You may
use `.REG' at will to redefine register variables.
All these directives accept the variable name in the "label"
position, that is at the left margin. You may specify a colon after
the variable name if you wish; the first example above could have
started `eg:' with the same effect.

File:, Node: Macros, Next: Data, Prev: Variables, Up: Commands
Defining your own directives
The commands `.MACRO' and `.ENDM' allow you to define macros that
generate assembly output. You can use these macros with a syntax
similar to built-in GASP or assembler directives. For example, this
definition specifies a macro `SUM' that adds together a range of
consecutive registers:
mov r\FROM,r10
add r\&COUNT,r10
With that definition, `SUM 0,5' generates this assembly output:
! 0 5
mov r0,r10
add r1,r10
add r2,r10
add r3,r10
add r4,r10
add r5,r10
Begin the definition of a macro called MACNAME. If your macro
definition requires arguments, specify their names after the macro
name, separated by commas or spaces. You can supply a default
value for any macro argument by following the name with `=DEFLT'.
For example, these are all valid `.MACRO' statements:
Begin the definition of a macro called `COMM', which takes no
Either statement begins the definition of a macro called
`PLUS1', which takes two arguments; within the macro
definition, write `\P' or `\P1' to evaluate the arguments.
Begin the definition of a macro called `RESERVE_STR', with two
arguments. The first argument has a default value, but not
the second. After the definition is complete, you can call
the macro either as `RESERVE_STR A,B' (with `\P1' evaluating
to A and `\P2' evaluating to B), or as `RESERVE_STR ,B' (with
`\P1' evaluating as the default, in this case `0', and `\P2'
evaluating to B).
When you call a macro, you can specify the argument values either
by position, or by keyword. For example, `SUM 9,17' is equivalent
to `SUM TO=17, FROM=9'. Macro arguments are preprocessor variables
similar to the variables you define with `.ASSIGNA' or `.ASSIGNC';
in particular, you can use them in conditionals or for loop
control. (The only difference is the prefix you write to evaluate
the variable: for a macro argument, write `\ARGNAME', but for a
preprocessor variable, write `\&VARNAME'.)
An alternative form of introducing a macro definition: specify the
macro name in the label position, and the arguments (if any)
between parentheses after the name. Defaulting rules and usage
work the same way as for the other macro definition syntax.
Mark the end of a macro definition.
Exit early from the current macro definition, `.AREPEAT' loop, or
`.AWHILE' loop.
GASP maintains a counter of how many macros it has executed in
this pseudo-variable; you can copy that number to your output with
`\@', but _only within a macro definition_.
`LOCAL NAME [ , ... ]'
_Warning: `LOCAL' is only available if you select "alternate macro
syntax" with `-a' or `--alternate'._ *Note Alternate macro
syntax: Alternate.
Generate a string replacement for each of the NAME arguments, and
replace any instances of NAME in each macro expansion. The
replacement string is unique in the assembly, and different for
each separate macro expansion. `LOCAL' allows you to write macros
that define symbols, without fear of conflict between separate
macro expansions.

File:, Node: Data, Next: Listings, Prev: Macros, Up: Commands
Data output
In assembly code, you often need to specify working areas of memory;
depending on the application, you may want to initialize such memory or
not. GASP provides preprocessor directives to help you avoid
repetitive coding for both purposes.
You can use labels as usual to mark the data areas.
* Menu:
* Initialized::
* Uninitialized::

File:, Node: Initialized, Next: Uninitialized, Up: Data
Initialized data
These are the GASP directives for initialized data, and the standard
GNU assembler directives they expand to:
Evaluate arithmetic expressions EXPR, and emit the corresponding
`as' directive (labelled with LAB). The unqualified `.DATA' emits
`.long'; `.DATA.B' emits `.byte'; `.DATA.W' emits `.short'; and
`.DATA.L' emits `.long'.
For example, `foo .DATA 1,2,3' emits `foo: .long 1,2,3'.
Make `as' emit REPEAT copies of the value of the expression EXPR
(using the `as' directive `.fill'). `.DATAB.B' repeats one-byte
values; `.DATAB.W' repeats two-byte values; and `.DATAB.L' repeats
four-byte values. `.DATAB' without a suffix repeats four-byte
values, just like `.DATAB.L'.
REPEAT must be an absolute expression with a positive value.
`.SDATA "STR" ...'
String data. Emits a concatenation of bytes, precisely as you
specify them (in particular, _nothing is added to mark the end_ of
the string). *Note String and numeric constants: Constants, for
details about how to write strings. `.SDATA' concatenates multiple
arguments, making it easy to switch between string
representations. You can use commas to separate the individual
arguments for clarity, if you choose.
Repeated string data. The first argument specifies how many
copies of the string to emit; the remaining arguments specify the
string, in the same way as the arguments to `.SDATA'.
`.SDATAZ "STR" ...'
Zero-terminated string data. Just like `.SDATA', except that
`.SDATAZ' writes a zero byte at the end of the string.
`.SDATAC "STR" ...'
Count-prefixed string data. Just like `.SDATA', except that GASP
precedes the string with a leading one-byte count. For example,
`.SDATAC "HI"' generates `.byte 2,72,73'. Since the count field
is only one byte, you can only use `.SDATAC' for strings less than
256 bytes in length.

File:, Node: Uninitialized, Prev: Initialized, Up: Data
Uninitialized data
Use the `.RES', `.SRES', `.SRESC', and `.SRESZ' directives to
reserve memory and leave it uninitialized. GASP resolves these
directives to appropriate calls of the GNU `as' `.space' directive.
Reserve room for COUNT uninitialized elements of data. The suffix
specifies the size of each element: `.RES.B' reserves COUNT bytes,
`.RES.W' reserves COUNT pairs of bytes, and `.RES.L' reserves
COUNT quartets. `.RES' without a suffix is equivalent to `.RES.L'.
`.SRES' is a synonym for `.RES'.
Like `.SRES', but reserves space for `COUNT+1' elements.
Like `.SRES', but reserves space for `COUNT+1' elements.

File:, Node: Listings, Next: Other Commands, Prev: Data, Up: Commands
Assembly listing control
The GASP listing-control directives correspond to related GNU `as'
Print control. This directive emits the GNU `as' directive
`.list' or `.nolist', according to its argument. *Note `.list':
(, for details on how these directives interact.
Specify the page size for assembly listings: LN represents the
number of lines, and COLS the number of columns. You may specify
either page dimension independently, or both together. If you do
not specify the number of lines, GASP assumes 60 lines; if you do
not specify the number of columns, GASP assumes 132 columns. (Any
values you may have specified in previous instances of `.FORM' do
_not_ carry over as defaults.) Emits the `.psize' assembler
Specify STRING as the title of your assembly listings. Emits
`.title "STRING"'.
Force a new page in assembly listings. Emits `.eject'.

File:, Node: Other Commands, Next: Syntax Details, Prev: Listings, Up: Commands
Miscellaneous commands
Use the alternate macro syntax henceforth in the assembly. *Note
Alternate macro syntax: Alternate.
This command is recognized, but not yet implemented. GASP
generates an error message for programs that use `.ORG'.
GASP understands numbers in any of base two, eight, ten, or
sixteen. You can encode the base explicitly in any numeric
constant (*note String and numeric constants: Constants.). If you
write numbers without an explicit indication of the base, the most
recent `.RADIX S' command determines how they are interpreted. S
is a single letter, one of the following:
Base 2.
Base 8.
Base 10. This is the original default radix.
Base 16.
You may specify the argument S in lower case (any of `bqdh') with
the same effects.
Declare NAME global (emits `.global NAME'). The two directives
are synonymous.
No effect: GASP accepts this directive, and silently ignores it.
Mark end of each preprocessor file. GASP issues a warning if it
reaches end of file without seeing this command.
Preprocess the file named by STR, as if its contents appeared
where the `.INCLUDE' directive does. GASP imposes a maximum limit
of 30 stacked include files, as a sanity check.
Evaluate the absolute expression SIZE, and emit the assembly
instruction `.align SIZE' using the result.

File:, Node: Syntax Details, Next: Alternate, Prev: Other Commands, Up: Commands
Details of the GASP syntax
Since GASP is meant to work with assembly code, its statement syntax
has no surprises for the assembly programmer.
_Whitespace_ (blanks or tabs; _not_ newline) is partially
significant, in that it delimits up to three fields in a line. The
amount of whitespace does not matter; you may line up fields in separate
lines if you wish, but GASP does not require that.
The _first field_, an optional "label", must be flush left in a line
(with no leading whitespace) if it appears at all. You may use a colon
after the label if you wish; GASP neither requires the colon nor
objects to it (but will not include it as part of the label name).
The _second field_, which must appear after some whitespace,
contains a GASP or assembly "directive".
Any _further fields_ on a line are "arguments" to the directive; you
can separate them from one another using either commas or whitespace.
* Menu:
* Markers::
* Constants::
* Symbols::
* Expressions::
* String Builtins::

File:, Node: Markers, Next: Constants, Up: Syntax Details
Special syntactic markers
GASP recognizes a few special markers: to delimit comments, to
continue a statement on the next line, to separate symbols from other
characters, and to copy text to the output literally. (One other
special marker, `\@', works only within macro definitions; *note
Defining your own directives: Macros..)
The trailing part of any GASP source line may be a "comment". A
comment begins with the first unquoted comment character (`!' by
default), or an escaped or doubled comment character (`\!' or `!!' by
default), and extends to the end of a line. You can specify what
comment character to use with the `-c' option (*note Command Line
Options: Invoking GASP.). The two kinds of comment markers lead to
slightly different treatment:
A single, un-escaped comment character generates an assembly
comment in the GASP output. GASP evaluates any preprocessor
variables (macro arguments, or variables defined with `.ASSIGNA' or
`.ASSIGNC') present. For example, a macro that begins like this
issues as the first line of output a comment that records the
values you used to call the macro.
Either an escaped comment character, or a double comment character,
marks a GASP source comment. GASP does not copy such comments to
the assembly output.
To _continue a statement_ on the next line of the file, begin the
second line with the character `+'.
Occasionally you may want to prevent GASP from preprocessing some
particular bit of text. To _copy literally_ from the GASP source to
its output, place `\(' before the string to copy, and `)' at the end.
For example, write `\(\!)' if you need the characters `\!' in your
assembly output.
To _separate a preprocessor variable_ from text to appear
immediately after its value, write a single quote (`''). For example,
`.SDATA "\P'1"' writes a string built by concatenating the value of `P'
and the digit `1'. (You cannot achieve this by writing just `\P1',
since `P1' is itself a valid name for a preprocessor variable.)

File:, Node: Constants, Next: Symbols, Prev: Markers, Up: Syntax Details
String and numeric constants
There are two ways of writing "string constants" in GASP: as literal
text, and by numeric byte value. Specify a string literal between
double quotes (`"STR"'). Specify an individual numeric byte value as
an absolute expression between angle brackets (`<EXPR>'. Directives
that output strings allow you to specify any number of either kind of
value, in whatever order is convenient, and concatenate the result.
(Alternate syntax mode introduces a number of alternative string
notations; *note Alternate macro syntax: Alternate..)
You can write "numeric constants" either in a specific base, or in
whatever base is currently selected (either 10, or selected by the most
recent `.RADIX').
To write a number in a _specific base_, use the pattern `S'DDD': a
base specifier character S, followed by a single quote followed by
digits DDD. The base specifier character matches those you can specify
with `.RADIX': `B' for base 2, `Q' for base 8, `D' for base 10, and `H'
for base 16. (You can write this character in lower case if you

File:, Node: Symbols, Next: Expressions, Prev: Constants, Up: Syntax Details
GASP recognizes symbol names that start with any alphabetic
character, `_', or `$', and continue with any of the same characters or
with digits. Label names follow the same rules.

File:, Node: Expressions, Next: String Builtins, Prev: Symbols, Up: Syntax Details
Arithmetic expressions in GASP
There are two kinds of expressions, depending on their result:
"absolute" expressions, which resolve to a constant (that is, they do
not involve any values unknown to GASP), and "relocatable" expressions,
which must reduce to the form
where ADDSYM and SUBSYM are assembly symbols of unknown value, and
CONST is a constant.
Arithmetic for GASP expressions follows very similar rules to C.
You can use parentheses to change precedence; otherwise, arithmetic
primitives have decreasing precedence in the order of the following
1. Single-argument `+' (identity), `-' (arithmetic opposite), or `~'
(bitwise negation). _The argument must be an absolute expression._
2. `*' (multiplication) and `/' (division). _Both arguments must be
absolute expressions._
3. `+' (addition) and `-' (subtraction). _At least one argument must
be absolute._
4. `&' (bitwise and). _Both arguments must be absolute._
5. `|' (bitwise or) and `~' (bitwise exclusive or; `^' in C). _Both
arguments must be absolute._

File:, Node: String Builtins, Prev: Expressions, Up: Syntax Details
String primitives
You can use these primitives to manipulate strings (in the argument
field of GASP statements):
Calculate the length of string `"STR"', as an absolute expression.
For example, `.RES.B .LEN("sample")' reserves six bytes of memory.
Search for the first occurrence of SEG after position IX of
STRING. For example, `.INSTR("ABCDEFG", "CDE", 0)' evaluates to
the absolute result `2'.
The result is `-1' if SEG does not occur in STRING after position
The substring of STRING beginning at byte number START and
extending for LEN bytes.

File:, Node: Alternate, Prev: Syntax Details, Up: Commands
Alternate macro syntax
If you specify `-a' or `--alternate' on the GASP command line, the
preprocessor uses somewhat different syntax. This syntax is
reminiscent of the syntax of Phar Lap macro assembler, but it is _not_
meant to be a full emulation of Phar Lap or similar assemblers. In
particular, GASP does not support directives such as `DB' and `IRP',
even in alternate syntax mode.
In particular, `-a' (or `--alternate') elicits these differences:
_Preprocessor directives_
You can use GASP preprocessor directives without a leading `.'
dot. For example, you can write `SDATA' with the same effect as
One additional directive, `LOCAL', is available. *Note Defining
your own directives: Macros, for an explanation of how to use
_String delimiters_
You can write strings delimited in these other ways besides
You can delimit strings with single-quote charaters.
You can delimit strings with matching angle brackets.
_single-character string escape_
To include any single character literally in a string (even if the
character would otherwise have some special meaning), you can
prefix the character with `!' (an exclamation mark). For example,
you can write `<4.3 !> 5.4!!>' to get the literal text `4.3 >
_Expression results as strings_
You can write `%EXPR' to evaluate the expression EXPR and use the
result as a string.

File:, Node: GNU Free Documentation License, Next: Index, Prev: Commands, Up: Top
GNU Free Documentation License
GNU Free Documentation License
Version 1.1, March 2000
Copyright (C) 2000 Free Software Foundation, Inc. 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA
Everyone is permitted to copy and distribute verbatim copies of
this license document, but changing it is not allowed.
The purpose of this License is to make a manual, textbook, or other
written document "free" in the sense of freedom: to assure everyone the
effective freedom to copy and redistribute it, with or without
modifying it, either commercially or noncommercially. Secondarily,
this License preserves for the author and publisher a way to get credit
for their work, while not being considered responsible for
modifications made by others.
This License is a kind of "copyleft", which means that derivative
works of the document must themselves be free in the same sense. It
complements the GNU General Public License, which is a copyleft license
designed for free software.
We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does. But this License is not limited to software manuals; it
can be used for any textual work, regardless of subject matter or
whether it is published as a printed book. We recommend this License
principally for works whose purpose is instruction or reference.
This License applies to any manual or other work that contains a
notice placed by the copyright holder saying it can be distributed
under the terms of this License. The "Document", below, refers to any
such manual or work. Any member of the public is a licensee, and is
addressed as "you".
A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
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A "Secondary Section" is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document's overall subject
(or to related matters) and contains nothing that could fall directly
within that overall subject. (For example, if the Document is in part a
textbook of mathematics, a Secondary Section may not explain any
mathematics.) The relationship could be a matter of historical
connection with the subject or with related matters, or of legal,
commercial, philosophical, ethical or political position regarding them.
The "Invariant Sections" are certain Secondary Sections whose titles
are designated, as being those of Invariant Sections, in the notice
that says that the Document is released under this License.
The "Cover Texts" are certain short passages of text that are listed,
as Front-Cover Texts or Back-Cover Texts, in the notice that says that
the Document is released under this License.
A "Transparent" copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the general
public, whose contents can be viewed and edited directly and
straightforwardly with generic text editors or (for images composed of
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for automatic translation to a variety of formats suitable for input to
text formatters. A copy made in an otherwise Transparent file format
whose markup has been designed to thwart or discourage subsequent
modification by readers is not Transparent. A copy that is not
"Transparent" is called "Opaque".
Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input format, SGML or
XML using a publicly available DTD, and standard-conforming simple HTML
designed for human modification. Opaque formats include PostScript,
PDF, proprietary formats that can be read and edited only by
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processing tools are not generally available, and the machine-generated
HTML produced by some word processors for output purposes only.
The "Title Page" means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the material
this License requires to appear in the title page. For works in
formats which do not have any title page as such, "Title Page" means
the text near the most prominent appearance of the work's title,
preceding the beginning of the body of the text.
You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License applies
to the Document are reproduced in all copies, and that you add no other
conditions whatsoever to those of this License. You may not use
technical measures to obstruct or control the reading or further
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compensation in exchange for copies. If you distribute a large enough
number of copies you must also follow the conditions in section 3.
You may also lend copies, under the same conditions stated above, and
you may publicly display copies.
If you publish printed copies of the Document numbering more than
100, and the Document's license notice requires Cover Texts, you must
enclose the copies in covers that carry, clearly and legibly, all these
Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts
on the back cover. Both covers must also clearly and legibly identify
you as the publisher of these copies. The front cover must present the
full title with all words of the title equally prominent and visible.
You may add other material on the covers in addition. Copying with
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If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
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If you publish or distribute Opaque copies of the Document numbering
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It is requested, but not required, that you contact the authors of
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You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release the
Modified Version under precisely this License, with the Modified
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and modification of the Modified Version to whoever possesses a copy of
it. In addition, you must do these things in the Modified Version:
A. Use in the Title Page (and on the covers, if any) a title distinct
from that of the Document, and from those of previous versions
(which should, if there were any, be listed in the History section
of the Document). You may use the same title as a previous version
if the original publisher of that version gives permission. B. List on
the Title Page, as authors, one or more persons or entities
responsible for authorship of the modifications in the Modified
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Document (all of its principal authors, if it has less than five). C.
State on the Title page the name of the publisher of the Modified
Version, as the publisher. D. Preserve all the copyright notices of
the Document. E. Add an appropriate copyright notice for your
modifications adjacent to the other copyright notices. F. Include,
immediately after the copyright notices, a license notice giving the
public permission to use the Modified Version under the terms of
this License, in the form shown in the Addendum below. G. Preserve in
that license notice the full lists of Invariant Sections and
required Cover Texts given in the Document's license notice. H.
Include an unaltered copy of this License. I. Preserve the section
entitled "History", and its title, and add to it an item stating at
least the title, year, new authors, and publisher of the Modified
Version as given on the Title Page. If there is no section entitled
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authors, and publisher of the Document as given on its Title Page,
then add an item describing the Modified Version as stated in the
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the Document for public access to a Transparent copy of the
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preserve the section's title, and preserve in the section all the
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titles. Section numbers or the equivalent are not considered part
of the section titles. M. Delete any section entitled "Endorsements".
Such a section may not be included in the Modified Version. N. Do
not retitle any existing section as "Endorsements" or to conflict in
title with any Invariant Section.
If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no material
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of these sections as invariant. To do this, add their titles to the
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These titles must be distinct from any other section titles.
You may add a section entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
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been approved by an organization as the authoritative definition of a
You may add a passage of up to five words as a Front-Cover Text, and
a passage of up to 25 words as a Back-Cover Text, to the end of the list
of Cover Texts in the Modified Version. Only one passage of
Front-Cover Text and one of Back-Cover Text may be added by (or through
arrangements made by) any one entity. If the Document already includes
a cover text for the same cover, previously added by you or by
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may not add another; but you may replace the old one, on explicit
permission from the previous publisher that added the old one.
The author(s) and publisher(s) of the Document do not by this License
give permission to use their names for publicity for or to assert or
imply endorsement of any Modified Version.
You may combine the Document with other documents released under this
License, under the terms defined in section 4 above for modified
versions, provided that you include in the combination all of the
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list them all as Invariant Sections of your combined work in its
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The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
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Make the same adjustment to the section titles in the list of Invariant
Sections in the license notice of the combined work.
In the combination, you must combine any sections entitled "History"
in the various original documents, forming one section entitled
"History"; likewise combine any sections entitled "Acknowledgements",
and any sections entitled "Dedications". You must delete all sections
entitled "Endorsements."
You may make a collection consisting of the Document and other
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy that
is included in the collection, provided that you follow the rules of
this License for verbatim copying of each of the documents in all other
You may extract a single document from such a collection, and
distribute it individually under this License, provided you insert a
copy of this License into the extracted document, and follow this
License in all other respects regarding verbatim copying of that
A compilation of the Document or its derivatives with other separate
and independent documents or works, in or on a volume of a storage or
distribution medium, does not as a whole count as a Modified Version of
the Document, provided no compilation copyright is claimed for the
compilation. Such a compilation is called an "aggregate", and this
License does not apply to the other self-contained works thus compiled
with the Document, on account of their being thus compiled, if they are
not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one quarter
of the entire aggregate, the Document's Cover Texts may be placed on
covers that surround only the Document within the aggregate. Otherwise
they must appear on covers around the whole aggregate.
Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section 4.
Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections. You may include a
translation of this License provided that you also include the original
English version of this License. In case of a disagreement between the
translation and the original English version of this License, the
original English version will prevail.
You may not copy, modify, sublicense, or distribute the Document
except as expressly provided for under this License. Any other attempt
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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.
The Free Software Foundation may publish new, revised versions of
the GNU Free Documentation 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. See
Each version of the License is given a distinguishing version number.
If the Document specifies that a particular numbered version of this
License "or any later version" applies to it, you have the option of
following the terms and conditions either of that specified version or
of any later version that has been published (not as a draft) by the
Free Software Foundation. If the Document does not specify a version
number of this License, you may choose any version ever published (not
as a draft) by the Free Software Foundation.
ADDENDUM: How to use this License for your documents
To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:
Copyright (c) YEAR YOUR NAME.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1
or any later version published by the Free Software Foundation;
with the Invariant Sections being LIST THEIR TITLES, with the
Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
A copy of the license is included in the section entitled "GNU
Free Documentation License".
If you have no Invariant Sections, write "with no Invariant Sections"
instead of saying which ones are invariant. If you have no Front-Cover
Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being
LIST"; likewise for Back-Cover Texts.
If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License, to
permit their use in free software.

File:, Node: Index, Prev: GNU Free Documentation License, Up: Top
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