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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<HTML>
<HEAD>
 <META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
 <TITLE>XINDY FAQ: Style Files</TITLE>
 <LINK HREF="faq-3.html" REL=previous>
 <LINK HREF="faq.html#toc4" REL=contents>
</HEAD>
<BODY>
Next
<A HREF="faq-3.html">Previous</A>
<A HREF="faq.html#toc4">Contents</A>
<HR>
<H2><A NAME="s4">4. Style Files</A></H2>

<H2><A NAME="ss4.1">4.1 Eventually, I decided to write my first index style. How can I start?</A>
</H2>

<P>
<P>Congratulations! You have made a good decision, indeed.
<P>For a first impression, how a style file can be written from scratch
reference the <EM>tutorial</EM> that comes with this distribution. It is
written as a guided step-by-step practicing exercise and you can learn
the basic concepts quite easily.
<P>Afterwards, the best starting point is to make a copy of the template
file that contains all the necessary commands that are needed to make
a <CODE>makeindex</CODE>-like index. You can find it in the subdirectory
<CODE>markup/tex</CODE> of the module library. Starting from this template
you can remove or add commands as necessary.
<P>Additionally, consult the library of predefined <EM>index style
modules</EM> that comes with this distribution. Solutions for most of the
typical problems can be found there, such as a module for doing
case-insensitive sorting rules, or a typical TeX-like markup. Most
of the time is is enough to include some of these modules and add a
few additional commands.
<P>Maybe some of the examples coming with the <EM>test-suite</EM> are good
examples of how unusual index style files can be written.
<P>Thus, there are many ways to learn writing an index style file. But it
is very easy and after some experience you can process indexes your
friends will be jealous of.
<P>
<P>
<H2><A NAME="ss4.2">4.2 How to write my first index style?</A>
</H2>

<P>
<P>Copy the file <CODE>tex/makeidx.xdy</CODE> from the library to your
local directory. It is documented in in a way that should make it easy
to fill in new commands or remove or modify others.
<P>
<P>
<P>
<H2><A NAME="ss4.3">4.3 How works the actual key feature of <CODE>makeindex</CODE> with <SF>xindy</SF>?</A>
</H2>

<P>
<P>The treatment of the actual key (usually denoted with <CODE>@</CODE>, the
at-sign) has changed with <SF>xindy</SF>. Specifying index entries with a
specific markup can be done in <CODE>makeindex</CODE> with the actual key. The
<CODE>makeindex-3</CODE> system and <SF>xindy</SF> offer the <EM>merge-</EM> and
<EM>sort-rules</EM> to transform a key into different representations,
limiting the need to specify an actual key. For example they support a
style of writing
<P>
<BLOCKQUOTE><CODE>
<PRE>
\index{\bf{VIP}}
</PRE>
</CODE></BLOCKQUOTE>
<P>which can be transformed with a rule like
<P>
<BLOCKQUOTE><CODE>
<PRE>
(merge-rule "\bf{\(.*\)}" "\1" :again :bregexp)
</PRE>
</CODE></BLOCKQUOTE>
<P>which removes the macro definition for merging and sorting keywords,
but keeping the original definition for markup purposes. Therefore we
don't need any actual keys for all keywords written in boldface.
<P>The <CODE>makeindex</CODE> behaviour, that the two keywords
<P>
<BLOCKQUOTE><CODE>
<PRE>
\index{VIP}
\index{VIP@\bf{VIP}}
</PRE>
</CODE></BLOCKQUOTE>
<P>are seen as two distinct index entries, can be simulated using the
following definition:
<P>
<BLOCKQUOTE><CODE>
<PRE>
(merge-rule "\bf{\(.*\)}" "\1~e" :again :bregexp)
</PRE>
</CODE></BLOCKQUOTE>
<P>This rule tells <SF>xindy</SF> to remove the boldface macro for merging
and sorting purposes but defines the replacement to include the
special character <CODE>~e</CODE>, which is the last character in the
alphabet (ISO-Latin in our case). This makes <SF>xindy</SF> treat them as
different keywords and positions the boldface keyword right behind the
one without any markup. Thus we receive the following mapping:
<P>
<BLOCKQUOTE><CODE>
<PRE>
Keyword:    Merged and sorted as:   Appears in the index as:
VIP              VIP                     VIP
\bf{VIP}         VIP~e                   \bf{VIP}
</PRE>
</CODE></BLOCKQUOTE>
<P>With this new style of writing keywords and defining their markup, the
need to explicitly specifying the print key (aka. actual key) has
convinced us to remove the <CODE>makeindex</CODE> way of defining keywords.
<P>
<P>
<P>
<H2><A NAME="ss4.4">4.4 I want to process an index for my native language. What must I do?</A>
</H2>

<P>
<P>What makes <CODE>makeindex</CODE> hardly usable in non-English speaking
countries is its lack of support of language specific alphabets and
sort orderings. For example, many roman languages such as Italian,
French, Portuguese or Spanish contain accented letters such as
&Agrave;, &Aacute;, &ntilde;. Other languages from northern Europe
have letters like &Auml;, &Oslash;, &aelig; or &szlig; which often
can't even be processed by many index processors let alone sorting
them correctly into an index.
<P>Two problems must be solved when processing indexes with a new
languages:
<P>
<OL>
<LI> The <EM>sort ordering</EM> of the indexed terms must be specified
in an appropriate manner. This problem can be solved using the
so-called <EM>keyword mappings</EM>.
</LI>
<LI> The <EM>letter groups</EM> that partition the indexed terms into
separate sections must be specified.</LI>
</OL>
<P>The <SF>xindy</SF> system can be configured to process these alphabets by
defining <EM>sort</EM> and <EM>merge rules</EM> that allow expressing language
specific rules.
<P>The keyword mappings are as follows: The <EM>merge key</EM> is generated
from the <EM>main key</EM> with the so called <EM>merge mapping</EM>. The
merge mapping can be specified with the command <CODE>merge-rule</CODE>. The
<EM>sort key</EM> is derived from the merge key using the <EM>sort
mapping</EM> specified with the <CODE>sort-rule</CODE> command. The following
scheme shows this mapping process:
<P>
<FIGURE>
<EPS FILE="mappings.eps">
<IMG SRC="mappings.gif">
</FIGURE>
<P>
<P>The index style commands accomplishing this task are
<CODE>sort-rule</CODE> and <CODE>merge-rule</CODE>. One example of such a rule would
be
<P>
<BLOCKQUOTE><CODE>
<PRE>
(sort-rule "ä" "ae")
</PRE>
</CODE></BLOCKQUOTE>
<P>defining that a word containing the umlaut-a will be sorted as if it
contained the letters <CODE>ae</CODE> instead. This is one form of how the
umlaut-a (ä) is sorted into german indexes. With an appropriate set of
rules on can express the complete rules of a specific language.
<P>An example of how an appropriate mapping for some of the Roman
languages could look like is:
<P>
<BLOCKQUOTE><CODE>
<PRE>
(sort-rule "à" "a")
(sort-rule "á" "a")
(sort-rule "ã" "a")
(sort-rule "è" "e")
(sort-rule "é" "e")
(sort-rule "ç" "c")
</PRE>
</CODE></BLOCKQUOTE>
<P>This makes the accented letters be sorted as their unaccented
counterparts, yielding the desired sort ordering.
<P>Sometimes it is necessary to specify keyword mappings that tell the
system to put something <EM>behind</EM> something else. For instance, we'd
like to map the character <EM>ö</EM> behind the letter <EM>o</EM>. No problem
if you use the special characters <CODE>~b</CODE> and <CODE>~e</CODE> which
are called the <EM>beginning</EM> and <EM>ending</EM> characters. The first
letter lexicographically precedes all other letters whereas the latter
one comes after all others. Our mapping problem can now be specified
as follows.
<P>
<BLOCKQUOTE><CODE>
<PRE>
(sort-rule "ö" "o~e")
</PRE>
</CODE></BLOCKQUOTE>
<P>Now the <EM>ö</EM> is directly positioned after the <EM>o</EM> but before
<EM>p</EM>.
<P>
<P>See the manual for a detailed description of this feature.
Also be informed that the keyword mappings can be specified with
regular expressions. Rules of the form
<P>
<BLOCKQUOTE><CODE>
<PRE>
(merge-rule "[-$()]" "")
</PRE>
</CODE></BLOCKQUOTE>
<P>are possible. This on removes all letters of the defined letter class.
Regular expression substitutions are possible as well. Refer to the
manual for an exact description.
<P>
<P>
<P>
<H2><A NAME="ss4.5">4.5 In my index the capitalized words appear after the lowercase words. Why?</A>
</H2>

<P>
<P>The default sort ordering sorts letters according to their ordinal
number in the ISO Latin alphabet. As a consequence the lowercase
letters appear before the uppercase letters. To sort them
case-insensitively use the command
<P>
<BLOCKQUOTE><CODE>
<PRE>
(require "lang/latin/caseisrt.xdy")
</PRE>
</CODE></BLOCKQUOTE>
<P>This module defines the appropriate sort rules for the letters `A-Z'
for latin-based alphabets. If your language has more letters simply
add the missing ones into your style file. Have a look at the module
to see how to the sort rules are defined.
<P>
<P>
<P>
<H2><A NAME="ss4.6">4.6 In my index there are no letter groups, yet!</A>
</H2>

<P>
<P>Letter groups for latin based alphabets can be defined with the command
<P>
<BLOCKQUOTE><CODE>
<PRE>
(require "lang/latin/letgroup.xdy")
</PRE>
</CODE></BLOCKQUOTE>
<P>If your language needs additional letter groups you can insert them
into the previously defined letter group with inserting definitions of
the following form:
<P>
<BLOCKQUOTE><CODE>
<PRE>
(define-letter-group "ly" :after "l" :before "m")
(define-letter-group "ny" :after "n" :before "o")
</PRE>
</CODE></BLOCKQUOTE>
<P>This adds two more letter groups to the latin alphabet. Group <EM>ly</EM>
is inserted between <EM>l</EM> and <EM>m</EM>, and <EM>ny</EM> is inserted between
<EM>n</EM> and <EM>o</EM>. This is how two additional letters of the Hungarian
alphabet can be inserted.
<P>
<P>
<P>
<H2><A NAME="ss4.7">4.7 How can I get rid of any formatting information in the keyword?</A>
</H2>

<P>
<P>Assume you have index entries containing arbitrary formatting
information. For example you write your index entries in TeX in the
following form:
<P>
<BLOCKQUOTE><CODE>
<PRE>
\index{\bf{In boldface please}}
</PRE>
</CODE></BLOCKQUOTE>
<P>To avoid specifying for each index entry the print key separately as
can be done with the following command
<P>
<BLOCKQUOTE><CODE>
<PRE>
\index{In boldface please@\bf{In boldface please}}
</PRE>
</CODE></BLOCKQUOTE>
<P>you can instead define a rule doing this task for you:
<P>
<BLOCKQUOTE><CODE>
<PRE>
(merge-rule "\\bf *{(.*)}" "\1" :eregexp :again)
</PRE>
</CODE></BLOCKQUOTE>
<P>This extended regular expression matches all strings that are
surrounded by this formatting command and in the <EM>merge phase</EM> the
formatting command is simply stripped off. Thus, you don't need to
write an explicit print key anymore.
<P>If for some reason the same word appears more than once in the index,
each time having another markup tag as in the following example
<P>
<BLOCKQUOTE><CODE>
<PRE>
index
{\tt index}
</PRE>
</CODE></BLOCKQUOTE>
<P>you must be warned that a rule like
<P>
<BLOCKQUOTE><CODE>
<PRE>
(merge-rule "{\\tt *(.*)}" "\1" :eregexp :again)
</PRE>
</CODE></BLOCKQUOTE>
<P>is probably not correct. In this case the above strings are both
mapped into the string <CODE>index</CODE> thus joining their location
references into one index entry. This happens because the result of
the merge mapping is used as the equality citerium which views both
keywords as equal. To avoid this you should specify instead
<P>
<BLOCKQUOTE><CODE>
<PRE>
(merge-rule "{\\tt *(.*)}" "\1~e" :eregexp :again)
</PRE>
</CODE></BLOCKQUOTE>
<P>With the additional meta character <CODE>~e</CODE> the substitution of the
second key word is placed <EM>after</EM> the first one making them
different index entries. If the second keyword should appear first,
use <CODE>~b</CODE> instead.
<P>
<P>
<P>
<P>
<H2><A NAME="ss4.8">4.8 In my index the word <EM>-foo</EM> appears before <EM>bar</EM>. What must I do?</A>
</H2>

<P>
<P>Especially for hierarchical indexes sometimes the result is not as
expected due to special characters appearing in the keyword. In the
following example the word `card' should appear before `-eyed' since
the hyphen should not count as an ordinary character by means of
sorting.
<P>
<BLOCKQUOTE><CODE>
<PRE>
  green
     -eyed  12
     card   15
</PRE>
</CODE></BLOCKQUOTE>
<P>This is especially problematic if the list of words on the second
level is very long. To make the hyphen be simply ignored during the
sorting process you should specify the following command in the index
style:
<P>
<BLOCKQUOTE><CODE>
<PRE>
  (sort-rule "-" "")
</PRE>
</CODE></BLOCKQUOTE>
<P>This makes `-eyed' be sorted as `eyed' thus making it appear
<EM>after</EM> `card' as desired.
<P>
<P>
<P>
<P>
<H2><A NAME="ss4.9">4.9 I want to use letter ordering instead of word ordering in my index.</A>
</H2>

<P>
<P>According to the <EM>Chicago Manual of Style</EM> there exist two
different schemes of sorting word lists. In <EM>word ordering</EM>
a blank precedes any letter in the alphabet, whereas in <EM>letter
ordering</EM> it does not count at all. The following example borrowed
from the <CODE>makeindex</CODE> man-page illustrates the difference:
<P>
<BLOCKQUOTE><CODE>
<PRE>
 Word Order:         Letter Order:
  sea lion            seal
  seal                sea lion
</PRE>
</CODE></BLOCKQUOTE>
<P>By default, <SF>xindy</SF> uses word ordering. To use letter ordering
include the appropriate module with the following command:
<P>
<BLOCKQUOTE><CODE>
<PRE>
(require "ord/letorder.xdy")
</PRE>
</CODE></BLOCKQUOTE>
<P>It actually defines the following command:
<P>
<BLOCKQUOTE><CODE>
<PRE>
(sort-rule " " "")
</PRE>
</CODE></BLOCKQUOTE>
<P>This simply removes all blanks from the keyword resulting in the
desired behaviour.
<P>
<P>
<P>
<P>
<H2><A NAME="ss4.10">4.10 My document does not have page numbers, but a different scheme. What must I do?</A>
</H2>

<P>
<P>The ability to deal with user-definable location structures is one of
the most important new features of <SF>xindy</SF>. Many documents have a
document structure that is not based on page numbers. Typical examples
are manuals or appendices that come with a
<EM>chapter/page-per-chapter</EM> numbering scheme, URLs, Bible verses,
etc. One can even imagine the Greek alphabet as possibly appearing in
a location reference. In our analysis we have found many interesting
examples of location references that made us to develop the concept of
<EM>location classes</EM>.
<P>A location class is defined by a sequence of alphabets. An alphabet
can be the set of arabic numbers (0, 1, 2, ...) or the roman numerals
(i, ii, iii, ...). These are built-in alphabets in <SF>xindy</SF>.
Addtionally, one can define more alphabets in the index style with a
command like
<P>
<PRE>
  (define-alphabet "weekdays"
         ("mon" "tue" "wed" "thu" "fri" "sat" "sun"))
</PRE>
<P>Based on alphabets one can now compose a location class as follows:
<P>
<PRE>
  (define-location-class "weekday-hours"
         ("weekday" :sep ":" "arabic-numbers"))
</PRE>
<P>This class description indicates that all location refernces matching
this template are viewed as correct instances of this class. Here
<CODE>:sep</CODE> makes the dot serving as a <EM>separation string</EM> separation
the alphabets from each other. Example instances of this class are:
<P>
<PRE>
mon:23, thu:45, sun:17
</PRE>
<P>For more detailed information consult the description of the command
<CODE>define-location-class</CODE> in the reference manual.
<P>
<P>
<P>
<H2><A NAME="ss4.11">4.11 I don't want to have ranges in my index. What can I do?</A>
</H2>

<P>
<P>By default, <SF>xindy</SF> joins three successive location references into a
<EM>range</EM>. Ranges are used as an abbrevation for a long sequence of
location references. For exmaple the sequence
<P>
<PRE>
12, 13, 14, 15, 16
</PRE>
<P>would be shorter represented as
<P>
<PRE>
12-16
</PRE>
<P>If you don't want to have ranges, simply define your location class in
the form
<P>
<PRE>
  (define-location-class ... :min-range-length none)
</PRE>
<P>The argument <CODE>:min-range-length none</CODE> avoids forming of ranges.
Arbitrary numbers instead of <CODE>none</CODE> define the minimum length of a
sequence of location references that are needed to form a range.
<SF>xindy</SF>s default value is&nbsp;2.
<P>
<P>
<P>
<H2><A NAME="ss4.12">4.12 I want to markup ranges of different length differently. How do I accomplish this?</A>
</H2>

<P>
<P>A common way of tagging ranges is as follows: a range of length 1 is
printed with the starting page number and the suffix `f.', those of
length 2 with suffix `ff.', and all others in the form `<EM>X--Y</EM>'.
<P>Assume we want to do this for the location class <EM>pagenums</EM> we can
specify the markup as follows:
<P>
<BLOCKQUOTE><CODE>
<PRE>
(markup-range :class "pagenums" :close "f."  :length 1 :ignore-end)
(markup-range :class "pagenums" :close "ff." :length 2 :ignore-end)
(markup-range :class "pagenums" :sep "--")
</PRE>
</CODE></BLOCKQUOTE>
<P>The first command indicates that a range <EM>(X,Y)</EM> of length 1 should
be printed in the form <EM>Xf.</EM>, a range of length 2 as <EM>Xff.</EM> and
all others in the form <EM>X--Y</EM>. The switch <CODE>:ignore-end</CODE> causes
the end of range location reference Y to be suppressed in the
resulting output.
<P>
<P>
<H2><A NAME="ss4.13">4.13 I need to suppress some of the markup tags. How can I do this?</A>
</H2>

<P>Sometimes it is necessary to hide some of the parts of the index. If
you have a text formatter that allows comments or macros that possibly
expand to nothing, just define appropriate markup that makes things
invisible to the formatter. For example, with TeX you can define a
macro like this
<P>
<BLOCKQUOTE><CODE>
<PRE>
\def\ignore#1{}
</PRE>
</CODE></BLOCKQUOTE>
<P>If you additionally define markup like this
<P>
<BLOCKQUOTE><CODE>
<PRE>
(markup-index :open "\ignore{" :close "}")
</PRE>
</CODE></BLOCKQUOTE>
<P>you can throw away the complete index if you like, which would be a
real pity!
<P>
<P>
<P>
<H2><A NAME="ss4.14">4.14 Whats it all about those cross references?</A>
</H2>

<P>
<P>Cross references are references pointing to an item in the index
itself. Typical examples are:
<P>
<BLOCKQUOTE><CODE>
foo-bar <EM>see</EM> baz
</CODE></BLOCKQUOTE>
<P>With <CODE>makeindex</CODE> cross references could be specified with the
encapsulation mechanism. This has completely been removed in <SF>xindy</SF>
and we have made cross references real first-class objects.
<P>In <SF>xindy</SF> one can declare different cross reference classes, whose
purpose is (a) to make all instances of a certain class appear next to
each other, and (b) to specify appropriate markup with them.
<P>@begin-comment
One very interesting feature is the ability to <EM>check</EM> the validity
of cross-references.
@end-comment
<P><CODE>tex2xindy</CODE> recognises all index entries of the form
<P>
<PRE>
  \index{...|\macro{where}}
</PRE>
<P>as cross references. Here <CODE>macro</CODE> stands for an arbitrary macro
name and <CODE>where</CODE> is interpreted as the target keyword of the cross
references.
<P>If you want to use these cross references with <SF>xindy</SF>; add the
following line to your style file.
<P>
<PRE>
  (define-crossref-class "macro")
</PRE>
<P>Additionally, you can assign specific markup to cross references using
the <CODE>markup-crossref</CODE>-commands.
<P>
<P>
<P>
<H2><A NAME="ss4.15">4.15 The keyword mappings don't work as expected!</A>
</H2>

<P>
<P>Sometimes the keyword mappings don't work as expected. Especially in
cases with several regular expressions one might get confused about
what rule matches exactly when. We have incorporated a detailed
logging mechanism that lets one step by step follow the rules that
accomplish the keyword mapping.
<P>When running <SF>xindy</SF> you can turn on this feature with the command
line option `<CODE>-L</CODE>'. This option followed by one of the numbers 1,
2, or 3 turns on the appropriate debugging level. Turning on level 2
or 3 and specifying a log-file with the command line option `<CODE>-l</CODE>'
a trace of the mappings is recorded in the log-file. A sample output
looks like the following:
<P>
<BLOCKQUOTE><CODE>
<PRE>
Mappings: (add (merge-rule :eregexp `^\\bf{(.*)}' `\1' :again)).
Mappings: (add (merge-rule :eregexp `^\\"([AEOUaeou])' `\1')).
 ...
Mappings: (compare `\"A\"a' :eregexp `^\\bf{(.*)}')
Mappings: (compare `\"A\"a' :eregexp `^\\"([AEOUaeou])') match!
Mappings: (compare `\"a' :eregexp `^\\bf{(.*)}')
Mappings: (compare `\"a' :eregexp `^\\"([AEOUaeou])') match!
Mappings: (merge-mapping `\"A\"a') -> `Aa'.
</PRE>
</CODE></BLOCKQUOTE>
<P>This trace shows that initially two regular expression mappings have
been added to the rule set. The second section shows how the keyword
`<CODE>\"A\"a</CODE>' is compared to these rules and substitutions are
applied as matches are found. In the last line the result of the
keyword mapping is reported.
<P>
<P>
<P>
<H2><A NAME="ss4.16">4.16 I'm totally confused by the markup scheme!</A>
</H2>

<P>
<P>A very important feature is the ability to <EM>trace</EM> all markup tags
<SF>xindy</SF> emits in the markup phase. Simply use the command line
switch <CODE>-t</CODE> or insert the command
<P>
<BLOCKQUOTE><CODE>
<PRE>
(markup-trace :on)
</PRE>
</CODE></BLOCKQUOTE>
<P>into the index style. This informs <SF>xindy</SF> to emit additional
pseudo markup that can be used to understand and debug the
markup phase. An example output might look like the following:
<P>
<BLOCKQUOTE><CODE>
<PRE>
&lt;INDEX:OPEN>
  &lt;LETTER-GROUP-LIST:OPEN>
    &lt;LETTER-GROUP:OPEN ["a"]>
      &lt;INDEXENTRY-LIST:OPEN [0]>
        &lt;INDEXENTRY:OPEN [0]>
          &lt;KEYWORD-LIST:OPEN [0]>
            &lt;KEYWORD:OPEN [0]>
 ...
</PRE>
</CODE></BLOCKQUOTE>
<P>The symbolic tags directly lead one to the command that is responsible
for the definition of that markup tag. For example, the tag
<CODE>LETTER-GROUP-LIST:OPEN</CODE> indicates that the command
<CODE>markup-letter-group-list</CODE> is responsible for replacing this
symbolic tag by a real one.
Give it a try if you find yourself confused by your own markup
specification.
<P>
<P>
<P>
<H2><A NAME="ss4.17">4.17 What editor should I use when writing xindy style files?</A>
</H2>

<P>
<P>Use <CODE>Emacs</CODE> or <CODE>XEmacs</CODE>. Turn on the Lisp-mode with
<P>
<BLOCKQUOTE><CODE>
<PRE>
M-x lisp-mode
</PRE>
</CODE></BLOCKQUOTE>
<P>and you can properly indent commands using <CODE>M-q</CODE>. To enter this
mode automatically add the following lines to the end of the style
file:
<P>
<BLOCKQUOTE><CODE>
<PRE>
^L
;; Local Variables:
;; mode: lisp
;; End:
</PRE>
</CODE></BLOCKQUOTE>
<P>The <CODE>^L</CODE> (Control-L) can be entered with <CODE>C-q C-l</CODE>.
<P>
<P>
<P>
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