SGI Freeware 2002 November

home *** CD-ROM | disk | FTP | other *** search

/ SGI Freeware 2002 November / SGI Freeware 2002 November - Disc 1.iso / dist / fw_ddd.idb / usr / freeware / info / ddd-themes.info-2.z / ddd-themes.info-2

Wrap

Text File | 2001-10-09 | 49KB | 1,333 lines

This is ddd-themes.info, produced by makeinfo version 4.0 from ddd-themes.texi. INFO-DIR-SECTION Miscellaneous START-INFO-DIR-ENTRY * DDD-Themes: (ddd-themes). Writing DDD Themes. END-INFO-DIR-ENTRY DDD is a graphical front-end for GDB and other command-line debuggers. This is the First Edition, 2001-02-01, of `Writing DDD themes' for DDD Version 3.3.1. Copyright (C) 2001 UniversitΣt Passau Lehrstuhl fⁿr Software-Systeme Innstra▀e 33 D-94032 Passau GERMANY Distributed by Free Software Foundation, Inc. 59 Temple Place - Suite 330 Boston, MA 02111-1307 USA DDD and this manual are available via the DDD WWW page (http://www.gnu.org/software/ddd/). 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 no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License". Send questions, comments, suggestions, etc. to <ddd@gnu.org>. Send bug reports to <bug-ddd@gnu.org>. File: ddd-themes.info, Node: Color Functions, Next: Arc Functions, Prev: Font Functions, Up: VSL Library Color Functions =============== The functions in this section require inclusion of the library `colors.vsl'. For themes, `colors.vsl' need not be included explicitly. - VSL Function: color (box, foreground [, background]]) Returns BOX, where the foreground color will be drawn using the FOREGROUND color. If BACKGROUND is specified as well, it will be used for drawing the background. Both FOREGROUND and BACKGROUND are strings specifying a valid X11 color. File: ddd-themes.info, Node: Arc Functions, Next: Slope Functions, Prev: Color Functions, Up: VSL Library Arc Functions ============= The functions in this section require inclusion of the library `arcs.vsl'. For themes, `arcs.vsl' _must_ be included explicitly, using a line #include <arcs.vsl> at the beginning of the theme. * Menu: * Arc Basics:: * Custom Arc Functions:: File: ddd-themes.info, Node: Arc Basics, Next: Custom Arc Functions, Up: Arc Functions Arc Basics ---------- - VSL Function: arc (start, length [, thickness]) Returns a stretchable box with an arc of LENGTH, starting at angle START. START and LENGTH must be multiples of 90 (degrees). The angle of START is specified clockwise relative to the 9 o'clock position. THICKNESS defaults to `arcthickness()' (see below). - VSL Function: arcthickness () Default width of arcs. Defaults to `rulethickness()'. File: ddd-themes.info, Node: Custom Arc Functions, Prev: Arc Basics, Up: Arc Functions Custom Arc Functions -------------------- - VSL Function: oval (box) Returns an oval containing BOX. Example: `oval("33")'. - VSL Function: ellipse (box) - VSL Function: ellipse () Returns an ellipse containing BOX. Example: `ellipse("START")'. If BOX is omitted, the ellipse is stretchable and expands to the available space. - VSL Function: circle (box) Returns a circle containing BOX. Example: `circle(10)'. File: ddd-themes.info, Node: Slope Functions, Prev: Arc Functions, Up: VSL Library Slope Functions =============== The functions in this section require inclusion of the library `slopes.vsl'. For themes, `slopes.vsl' _must_ be included explicitly, using a line #include <slopes.vsl> at the beginning of the theme. * Menu: * Slope Basics:: * Arrow Functions:: * Custom Slope Functions:: File: ddd-themes.info, Node: Slope Basics, Next: Arrow Functions, Up: Slope Functions Slope Basics ------------ - VSL Function: rise ([thickness]) Create a stretchable box with a line from the lower left to the upper right corner. THICKNESS defaults to `slopethickness()' (see below). - VSL Function: fall ([thickness]) Create a stretchable box with a line from the upper left to the lower right corner. THICKNESS defaults to `slopethickness()' (see below). - VSL Function: slopethickness () Default thickness of slopes. Defaults to `rulethickness()'. File: ddd-themes.info, Node: Arrow Functions, Next: Custom Slope Functions, Prev: Slope Basics, Up: Slope Functions Arrow Functions --------------- - VSL Function: n_arrow () - VSL Function: w_arrow () - VSL Function: s_arrow () - VSL Function: e_arrow () Returns a box with an arrow pointing to the upper, left, lower, or right side, respectively. - VSL Function: nw_arrow () - VSL Function: ne_arrow () - VSL Function: sw_arrow () - VSL Function: se_arrow () Returns a box with an arrow pointing to the upper left, upper right, lower left, or lower right side, respectively. File: ddd-themes.info, Node: Custom Slope Functions, Prev: Arrow Functions, Up: Slope Functions Custom Slope Functions ---------------------- - VSL Function: punchcard (box) Returns a punchcard containing BOX. - VSL Function: rhomb (box) Returns a rhomb containing BOX. - VSL Function: octogon (box) Returns an octogon containing BOX. File: ddd-themes.info, Node: VSL Reference, Next: Documentation License, Prev: VSL Library, Up: Top VSL Reference ************* This appendix describes the VSL language. * Menu: * VSL Boxes:: * VSL Lists:: * VSL Expressions:: * VSL Function Calls:: * VSL Constant Definitions:: * VSL Function Definitions:: * VSL Includes:: * VSL Operators:: * VSL Syntax Summary:: File: ddd-themes.info, Node: VSL Boxes, Next: VSL Lists, Up: VSL Reference Boxes ===== VSL knows two data types. The most common data type is the _box_. A box is a rectangular area with a _content_, a _size_, and a _stretchability_. Boxes are either _atomic_ or _composite_. A composite box is built from two or more other boxes. These boxes can be aligned horizontally, vertically, or otherwise. Boxes have a specific minimum _size_, depending on their content. We say `minimum' size here, because some boxes are _stretchable_--that is, they can fill up the available space. If you have a vertical alignment of three boxes A, B, and C, like this: AAAAAA AAAAAA B B CCCCCC CCCCCC and B is stretchable horizontally, then B will fill up the available horizontal space: AAAAAA AAAAAA BBBBBB BBBBBB CCCCCC CCCCCC If two or more boxes compete for the same space, the space will be distributed in proportion to their stretchability. An atomic stretchable box has a stretchability of 1. An alignment of multiple boxes stretchable in the direction of the alignment boxes will have a stretchability which is the sum of all stretchabilities. If you have a vertical alignment of three boxes A, B, C, D, and E, like this: AAAAAA AAAAAA BC D BC D EEEEEE EEEEEE and B, C, and D are stretchable horizontally (with a stretchability of 1), then the horizontal alignment of B and C will have a stretchability of 2. Thus, the alignment of B and C gets two thirds of the available space; D gets the remaining third. AAAAAA AAAAAA BBCCDD BBCCDD EEEEEE EEEEEE File: ddd-themes.info, Node: VSL Lists, Next: VSL Expressions, Prev: VSL Boxes, Up: VSL Reference Lists ===== Besides boxes, VSL knows _lists_. A list is not a box--it has no size or stretchability. A list is a simple means to structure data. VSL lists are very much like lists in functional languages like Lisp or Scheme. They consist of a head (typically a list element) and a tail (which is either a list remainder or the empty list). File: ddd-themes.info, Node: VSL Expressions, Next: VSL Function Calls, Prev: VSL Lists, Up: VSL Reference Expressions =========== * Menu: * VSL String Literals:: * VSL Number Literals:: * VSL List Literals:: * VSL Conditionals:: * VSL Boolean Operators:: * VSL Local Variables:: * VSL Let Patterns:: File: ddd-themes.info, Node: VSL String Literals, Next: VSL Number Literals, Up: VSL Expressions String Literals --------------- The expression `"TEXT"' returns a box containing TEXT. TEXT is parsed according to C syntax rules. Multiple string expressions may follow each other to form a larger constant, as in C++. `"TEXT1" "TEXT2"' is equivalent to `"TEXT1TEXT2"' Strings are not stretchable. File: ddd-themes.info, Node: VSL Number Literals, Next: VSL List Literals, Prev: VSL String Literals, Up: VSL Expressions Number Literals --------------- Any constant integer N evaluates to a _number_--that is, a non-stretchable empty square box with size (N, N). File: ddd-themes.info, Node: VSL List Literals, Next: VSL Conditionals, Prev: VSL Number Literals, Up: VSL Expressions List Literals ------------- The expression `[A, B, ...]' evaluates to a _list_ containing the element A, B, .... `[]' is the empty list. The expression `[HEAD : TAIL]' evaluates to a list whose first element is HEAD and whose remainder (typically a list) is TAIL. In most contexts, round parentheses can be used as alternatives to square brackets. Thus, `(A, B)' is a list with two elements, and `()' is the empty list. Within an expression, though, square parentheses must be used to create a list with one element. In an expression, the form `(A)' is not a list, but an alternative notation for A. File: ddd-themes.info, Node: VSL Conditionals, Next: VSL Boolean Operators, Prev: VSL List Literals, Up: VSL Expressions Conditionals ------------ A box A = (A1, A2) is called _true_ if A1 or A2 is non-zero. It is called _false_ if both A1 or A2 are zero. The special form if A then B else C fi returns B if A is true, and C otherwise. Only one of B or C is evaluated. The special form elsif A2 then B2 else C fi is equivalent to else if A2 then B2 else C fi fi File: ddd-themes.info, Node: VSL Boolean Operators, Next: VSL Local Variables, Prev: VSL Conditionals, Up: VSL Expressions Boolean Operators ----------------- The special form A and B is equivalent to if A then B else 0 fi The special form A or B is equivalent to if A then 1 else B fi The special form not A is equivalent to if A then 0 else 1 fi Actually, `not' is realized as a function; *Note Negation Functions::, for details. File: ddd-themes.info, Node: VSL Local Variables, Next: VSL Let Patterns, Prev: VSL Boolean Operators, Up: VSL Expressions Local Variables --------------- You can introduce local variables using `let' and `where': let V1 = E1 in E makes V1 available as replacement for E1 in the expression E. Example: let pi = 3.1415 in 2 * pi => 6.2830 The special form let V1 = E1, V2 = E2, ... in E is equivalent to let V1 = E1 in let V2 = E2 in let ... in E As an alternative, you can also use the `where' form: E where V1 = E1 is equivalent to let V1 = E1 in E Example: ("here lies" | name) where name = ("one whose name" | "was writ in water") The special form E where V1 = E1, V2 = E2, ... is equivalent to let V1 = E1, V2 = E2, ... in E File: ddd-themes.info, Node: VSL Let Patterns, Prev: VSL Local Variables, Up: VSL Expressions Let Patterns ------------ You can access the individual elements of a list or some composite box by giving an appropriate _pattern_: let (left, right) = pair in EXPR If `pair' has the value, say, `(3, 4)', then `left' will be available as a replacement for `3', and `right' will be available as a replacement for `4' in EXPR. A special pattern is available for accessing the head and the tail of a list: let [head : tail] = list in EXPR If `expr' has the value, say, `[3, 4, 5]', then `head' will be `3', and `tail' will be `[4, 5]' in EXPR. File: ddd-themes.info, Node: VSL Function Calls, Next: VSL Constant Definitions, Prev: VSL Expressions, Up: VSL Reference Function Calls ============== A function call takes the form NAME LIST which invokes the (previously declared or defined) function with an argument of LIST. Normally, LIST is a list literal (*note VSL List Literals::) written with round brackets. File: ddd-themes.info, Node: VSL Constant Definitions, Next: VSL Function Definitions, Prev: VSL Function Calls, Up: VSL Reference Constant Definitions ==================== A VSL file consists of a list of _definitions_. A constant definition takes the form NAME = EXPRESSION; Any later definitions can use NAME as a replacement for EXPRESSION. Example: true = 1; false = 0; File: ddd-themes.info, Node: VSL Function Definitions, Next: VSL Includes, Prev: VSL Constant Definitions, Up: VSL Reference Function Definitions ==================== In VSL, all functions either map a _list_ to a _box_ or a _list_ to a _list_. A function definition takes the form NAME LIST = EXPRESSION; where LIST is a list literal (*note VSL List Literals::). The list literal is typically written in round parentheses, making the above form look like this: NAME(PARAM1, PARAM2, ...) = EXPRESSION; The `=' is replaced by `->' if NAME is a _global_ definition--that is, NAME can be called from a library client such as DDD. A _local_ definition (with `=') can be called only from other VSL functions.(1) * Menu: * VSL Function Parameters:: * VSL Function Patterns:: * VSL Declaring Functions:: * VSL Redefining Functions:: * VSL Replacing Functions:: * VSL Overriding Functions:: ---------- Footnotes ---------- (1) The distinction into global and local definitions is useful when optimizing the library: local definitions that are unused within the library can be removed, while global definitions cannot. File: ddd-themes.info, Node: VSL Function Parameters, Next: VSL Function Patterns, Up: VSL Function Definitions Function Parameters ------------------- The parameter list LIST may contain names of formal parameters. Upon a function call, these are bound to the actual arguments. If the function sum(a, b) = a + b; is called as sum(2. 3) then `a' will be bound to `2' and `b' will be bound to `3', evaluating to `5'. * Menu: * VSL Unused Parameters:: File: ddd-themes.info, Node: VSL Unused Parameters, Up: VSL Function Parameters VSL Unused Parameters ..................... Unused parameters cause a warning, as in this example: first_arg(a, dummy) = a; // Warning If a parameter has the name `_', it will not be bound to the actual argument (and can thus not be used). Use `_' as parameter name for unused arguments: first_arg(a, _) = a; // No warning `_' can be used multiple times in a parameter list. File: ddd-themes.info, Node: VSL Function Patterns, Next: VSL Declaring Functions, Prev: VSL Function Parameters, Up: VSL Function Definitions Function Patterns ----------------- A VSL function may have multiple definitions, each with a specific _pattern_. The first definition whose pattern _matches_ the actual argument is used. What does `matching' mean? Within a pattern, * An ordinary formal parameter matches any single value * A formal parameter whose name is `...' or ends in `...' matches a single value or a list or a list remainder * A constant matches exactly the same value * A composite box or list matches a composite box or list if - the composites have the same type - the composites have the same number of elements - the elements match each other. Here are some examples. The `num()' function (*note String Functions::) can take either one or two arguments. The one-argument definition simply invokes the two-argument definition: num(a, base) = ...; num(a) = num(a, 10); Here's another example: The `digit' function returns a string representation for a single number. It has multiple definitions, all dependent on the actual argument: digit(0) = "0"; digit(1) = "1"; digit(2) = "2"; digit(3) = "3"; digit(4) = "4"; digit(5) = "5"; digit(6) = "6"; digit(7) = "7"; digit(8) = "8"; digit(9) = "9"; digit(10) = "a"; digit(11) = "b"; digit(12) = "c"; digit(13) = "d"; digit(14) = "e"; digit(15) = "f"; digit(_) = fail("invalid digit() argument"); Formal parameters ending in `...' are useful for defining _aliases_ of functions. The definition roman(...) = rm(...); makes `roman' an alias of `rm'--any parameters (regardless how many) passed to `roman' will be passed to `rm'. Here's an example of how formal parameters ending in `...' can be used to realize _variadic functions_, taking any number of arguments (*note Maximum and Minimum Functions::): max(a) = a; max(a, b, ...) = if a > b then max(a, ...) else max(b, ...) fi; min(a) = a; min(a, b, ...) = if a < b then min(a, ...) else min(b, ...) fi; File: ddd-themes.info, Node: VSL Declaring Functions, Next: VSL Redefining Functions, Prev: VSL Function Patterns, Up: VSL Function Definitions Declaring Functions ------------------- If you want to use a function before it has been defined, just write down its signature without specifying a body. Here's an example: num(a, base); // declaration num(a) = num(a, 10); Remember to give a definition later on, though. File: ddd-themes.info, Node: VSL Redefining Functions, Next: VSL Replacing Functions, Prev: VSL Declaring Functions, Up: VSL Function Definitions Redefining Functions -------------------- You can redefine a VSL function even _after_ its original definition. You can * _replace_ the original definition, thus making all previous definitions refer to your new definition; * _override_ the original definition, thus making only later definitions refer to your new definition. File: ddd-themes.info, Node: VSL Replacing Functions, Next: VSL Overriding Functions, Prev: VSL Redefining Functions, Up: VSL Function Definitions Replacing Functions ------------------- To remove an original definition, use #pragma replace NAME This removes all previous definitions of NAME. Be sure to provide your own definitions, though. `#pragma replace' is typically used to change defaults: #include "fonts.vsl" // defines stdfontsize() #pragma replace stdfontsize() // replace def stdfontsize() = 20; All existing function calls will now refer to the new definition. File: ddd-themes.info, Node: VSL Overriding Functions, Prev: VSL Replacing Functions, Up: VSL Function Definitions Overriding Functions -------------------- To override an original definition, use #pragma override NAME This makes all later definitions use your new definition of NAME. Earlier definitions, however, still refer to the old definition. `#pragma override' is typically used if you want to redefine a function while still refering to the old definition: #include "fonts.vsl" // defines stdfontsize() // Save old definition old_stdfontsize() = stdfontsize(); #pragma override stdfontsize() // Refer to old definition stdfontsize() = old_stdfontsize() * 2; Since we used `#pragma override', we can use `old_stdfontsize()' to refer to the original definition of `stdfontsize()'. File: ddd-themes.info, Node: VSL Includes, Next: VSL Operators, Prev: VSL Function Definitions, Up: VSL Reference Includes ======== In a VSL file, you can include at any part the contents of another VSL file, using one of the special forms #include "FILE" #include <FILE> The form `<FILE>' looks for VSL files in a number of standard directories; the form `"FILE"' first looks in the directory where the current file resides. Any included file is included only once. In DDD, you can set these places using the `vslPath' resource. *Note Customizing Display Appearance: (ddd)Customizing Display Appearance, for details. File: ddd-themes.info, Node: VSL Operators, Next: VSL Syntax Summary, Prev: VSL Includes, Up: VSL Reference Operators ========= VSL comes with a number of _inline operators,_ which can be used to compose boxes. With raising precedence, these are: or and = <> <= < >= > :: | ^ ~ & + - * / % not Except for `or' and `and', these operators are mapped to function calls. Each invocation of an operator `@' in the form `A @ B' gets translated to a call of the VSL function with the special name `(@)'. This VSL function can be defined just like any other VSL function. For instance, the expression `A + B' gets translated to a function call `(+)(a, b)'; `A & B' invokes `(&)(a, b)'. In the file `builtin.vsl', you can actually find definitions of these functions: (&)(...) = __op_halign(...); (+)(...) = __op_plus(...); The functions `__op_halign' and `__op_plus' are the names by which the `(&)' and `(+)' functions are implemented. In this document, though, we will not look further at these internals. Here are the places where the operator functions are described: * For `=' and `<>', *Note Comparison Functions::. * For `<=', `<', `>=', and `>', *Note Comparison Functions::. * For `::', *Note List Functions::. * For `|', `^', `~', and `&', *Note Composition Functions::. * For `+', `-', `*', `/', and `%', *Note Arithmetic Functions::. * For `not', *Note Negation Functions::. File: ddd-themes.info, Node: VSL Syntax Summary, Prev: VSL Operators, Up: VSL Reference Syntax Summary ============== The following file summarizes the syntax of VSL files. /*** VSL file ***/ file : item_list item_list : /* empty */ | item_list item item : function_declaration ';' | function_definition ';' | override_declaration | replace_declaration | include_declaration | line_declaration | ';' | error ';' /*** functions ***/ function_declaration : function_header function_header : function_identifier function_argument | function_identifier function_identifier : identifier | '(' '==' ')' | '(' '<>' ')' | '(' '>' ')' | '(' '>=' ')' | '(' '<' ')' | '(' '<=' ')' | '(' '&' ')' | '(' '|' ')' | '(' '^' ')' | '(' '~' ')' | '(' '+' ')' | '(' '-' ')' | '(' '*' ')' | '(' '/' ')' | '(' '%' ')' | '(' '::' ')' | '(' 'not' ')' identifier : IDENTIFIER function_definition : local_definition | global_definition local_definition : local_header function_body local_header : function_header '=' global_definition : global_header function_body global_header : function_header '->' function_body : box_expression_with_defs /*** expressions ***/ /*** let, where ***/ box_expression_with_defs: box_expression_with_wheres | 'let' var_definition in_box_expression in_box_expression : 'in' box_expression_with_defs | ',' var_definition in_box_expression box_expression_with_wheres: box_expression | box_expression_with_where box_expression_with_where: box_expression_with_wheres 'where' var_definition | box_expression_with_where ',' var_definition var_definition : box_expression '=' box_expression /*** basic expressions ***/ box_expression : '(' box_expression_with_defs ')' | list_expression | const_expression | binary_expression | unary_expression | cond_expression | function_call | argument_or_function list_expression : '[' ']' | '[' box_expression_list ']' | '(' ')' | '(' multiple_box_expression_list ')' box_expression_list : box_expression_with_defs | multiple_box_expression_list multiple_box_expression_list: box_expression ':' box_expression | box_expression ',' box_expression_list | box_expression '...' | '...' const_expression : string_constant | numeric_constant string_constant : STRING | string_constant STRING numeric_constant : INTEGER function_call : function_identifier function_argument unary_expression : 'not' box_expression | '+' box_expression | '-' box_expression /*** operators ***/ binary_expression : box_expression '=' box_expression | box_expression '<>' box_expression | box_expression '>' box_expression | box_expression '>=' box_expression | box_expression '<' box_expression | box_expression '<=' box_expression | box_expression '&' box_expression | box_expression '|' box_expression | box_expression '^' box_expression | box_expression '~' box_expression | box_expression '+' box_expression | box_expression '-' box_expression | box_expression '*' box_expression | box_expression '/' box_expression | box_expression '%' box_expression | box_expression '::' box_expression | box_expression 'or' box_expression | box_expression 'and' box_expression cond_expression : 'if' box_expression 'then' box_expression_with_defs else_expression 'fi' else_expression : 'elsif' box_expression 'then' box_expression_with_defs else_expression | 'else' box_expression_with_defs function_argument : list_expression | '(' box_expression_with_defs ')' argument_or_function : identifier /*** directives ***/ override_declaration : '#pragma' 'override' override_list override_list : override_identifier | override_list ',' override_identifier override_identifier : function_identifier replace_declaration : '#pragma' 'replace' replace_list replace_list : replace_identifier | replace_list ',' replace_identifier replace_identifier : function_identifier include_declaration : '#include' '"' SIMPLE_STRING '"' | '#include' '<' SIMPLE_STRING '>' line_declaration : '#line' INTEGER | '#line' INTEGER STRING File: ddd-themes.info, Node: Documentation License, Next: Index, Prev: VSL Reference, Up: Top 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. 0. PREAMBLE 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. 1. APPLICABILITY AND DEFINITIONS 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 modifications and/or translated into another language. 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 pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or 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 proprietary word processors, SGML or XML for which the DTD and/or 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. 2. VERBATIM COPYING 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 copying of the copies you make or distribute. However, you may accept 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. 3. COPYING IN QUANTITY 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 changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects. If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages. If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a publicly-accessible computer-network location containing a complete Transparent copy of the Document, free of added material, which the general network-using public has access to download anonymously at no charge using public-standard network protocols. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public. It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document. 4. MODIFICATIONS 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 Version filling the role of the Document, thus licensing distribution 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 Version, together with at least five of the principal authors of the 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 "History" in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence. J. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the "History" section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission. K. In any section entitled "Acknowledgements" or "Dedications", preserve the section's title, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein. L. Preserve all the Invariant Sections of the Document, unaltered in their text and in their 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 copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version's license notice. 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 parties-for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard. 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 arrangement made by the same entity you are acting on behalf of, you 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. 5. COMBINING DOCUMENTS 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 Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice. The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. 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." 6. COLLECTIONS OF DOCUMENTS 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 respects. 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 document. 7. AGGREGATION WITH INDEPENDENT WORKS 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. 8. TRANSLATION 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. 9. TERMINATION You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Document 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. 10. FUTURE REVISIONS OF THIS LICENSE 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 http://www.gnu.org/copyleft/. 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.