- <variablelist>
-
- <varlistentry>
- <term>index <emphasis>field type code</emphasis></term>
- <listitem>
- <para>
- This directive introduces a new search index code.
- The argument is a one-character code to be used in the
- .abs files to select this particular index type. An index, roughly,
- corresponds to a particular structure attribute during search. Refer
- to <xref linkend="search"/>.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>sort <emphasis>field code type</emphasis></term>
- <listitem>
- <para>
- This directive introduces a
- sort index. The argument is a one-character code to be used in the
- .abs fie to select this particular index type. The corresponding
- use attribute must be used in the sort request to refer to this
- particular sort index. The corresponding character map (see below)
- is used in the sort process.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>completeness <emphasis>boolean</emphasis></term>
- <listitem>
- <para>
- This directive enables or disables complete field indexing.
- The value of the <emphasis>boolean</emphasis> should be 0
- (disable) or 1. If completeness is enabled, the index entry will
- contain the complete contents of the field (up to a limit), with words
- (non-space characters) separated by single space characters
- (normalized to " " on display). When completeness is
- disabled, each word is indexed as a separate entry. Complete subfield
- indexing is most useful for fields which are typically browsed (eg.
- titles, authors, or subjects), or instances where a match on a
- complete subfield is essential (eg. exact title searching). For fields
- where completeness is disabled, the search engine will interpret a
- search containing space characters as a word proximity search.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>charmap <emphasis>filename</emphasis></term>
- <listitem>
- <para>
- This is the filename of the character
- map to be used for this index for field type.
- </para>
- </listitem></varlistentry>
- </variablelist>
- </para>
-
- <para>
- The contents of the character map files are structured as follows:
- </para>
-
- <para>
- <variablelist>
-
- <varlistentry>
- <term>lowercase <emphasis>value-set</emphasis></term>
- <listitem>
- <para>
- This directive introduces the basic value set of the field type.
- The format is an ordered list (without spaces) of the
- characters which may occur in "words" of the given type.
- The order of the entries in the list determines the
- sort order of the index. In addition to single characters, the
- following combinations are legal:
- </para>
-
- <para>
-
- <itemizedlist>
- <listitem>
- <para>
- Backslashes may be used to introduce three-digit octal, or
- two-digit hex representations of single characters
- (preceded by <literal>x</literal>).
- In addition, the combinations
- \\, \\r, \\n, \\t, \\s (space — remember that real
- space-characters may ot occur in the value definition), and
- \\ are recognised, with their usual interpretation.
- </para>
- </listitem>
-
- <listitem>
- <para>
- Curly braces {} may be used to enclose ranges of single
- characters (possibly using the escape convention described in the
- preceding point), eg. {a-z} to entroduce the
- standard range of ASCII characters.
- Note that the interpretation of such a range depends on
- the concrete representation in your local, physical character set.
- </para>
- </listitem>
-
- <listitem>
- <para>
- paranthesises () may be used to enclose multi-byte characters -
- eg. diacritics or special national combinations (eg. Spanish
- "ll"). When found in the input stream (or a search term),
- these characters are viewed and sorted as a single character, with a
- sorting value depending on the position of the group in the value
- statement.
- </para>
- </listitem>
-
- </itemizedlist>
-
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>uppercase <emphasis>value-set</emphasis></term>
- <listitem>
- <para>
- This directive introduces the
- upper-case equivalencis to the value set (if any). The number and
- order of the entries in the list should be the same as in the
- <literal>lowercase</literal> directive.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>space <emphasis>value-set</emphasis></term>
- <listitem>
- <para>
- This directive introduces the character
- which separate words in the input stream. Depending on the
- completeness mode of the field in question, these characters either
- terminate an index entry, or delimit individual "words" in
- the input stream. The order of the elements is not significant —
- otherwise the representation is the same as for the
- <literal>uppercase</literal> and <literal>lowercase</literal>
- directives.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>map <emphasis>value-set</emphasis>
- <emphasis>target</emphasis></term>
- <listitem>
- <para>
- This directive introduces a
- mapping between each of the members of the value-set on the left to
- the character on the right. The character on the right must occur in
- the value set (the <literal>lowercase</literal> directive) of
- the character set, but
- it may be a paranthesis-enclosed multi-octet character. This directive
- may be used to map diacritics to their base characters, or to map
- HTML-style character-representations to their natural form, etc.
- </para>
- </listitem></varlistentry>
- </variablelist>
- </para>
-
- </sect2>
-
- </sect1>
-
- <sect1 id="formats">
- <title>Exchange Formats</title>
-
- <para>
- Converting records from the internal structure to en exchange format
- is largely an automatic process. Currently, the following exchange
- formats are supported:
- </para>
-
- <para>
- <itemizedlist>
- <listitem>
- <para>
- GRS-1. The internal representation is based on GRS-1/XML, so the
- conversion here is straightforward. The system will create
- applied variant and supported variant lists as required, if a record
- contains variant information.
- </para>
- </listitem>