Table of Contents
In order to provide a flexible approach to national character set handling, Zebra allows the administrator to configure the set up the system to handle any 8-bit character set — including sets that require multi-octet diacritics or other multi-octet characters. The definition of a character set includes a specification of the permissible values, their sort order (this affects the display in the SCAN function), and relationships between upper- and lowercase characters. Finally, the definition includes the specification of space characters for the set.
The operator can define different character sets for different fields, typical examples being standard text fields, numerical fields, and special-purpose fields such as WWW-style linkages (URx).
   Zebra 1.3 and Zebra versions 2.0.18 and earlier required that the field
   type is a single character, e.g. w (for word), and
   p for phrase. Zebra 2.0.20 and later allow field types 
   to be any string. This allows for greater flexibility - in particular
   per-locale (language) fields can be defined.
  
Version 2.1 of Zebra can also be configured - per field - to use the ICU library to perform tokenization and normalization of strings. This is an alternative to the "charmap" files which has been part of Zebra since its first release.
    The field types, and hence character sets, are associated with data
    elements by the indexing rules (say title:w) in the
    various filters. Fields are defined in a field definition file which,
    by default, is called default.idx. 
    This file provides the association between field type codes 
    and the character map files (with the .chr suffix). The format
    of the .idx file is as follows
   
field type codeThis 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 the section called “Z39.50 Search”.
field code typeThis 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.
boolean
	This directive enables or disables complete field indexing.
	The value of the boolean 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 (e.g.,
	titles, authors, or subjects), or instances where a match on a
	complete subfield is essential (e.g., exact title searching). For fields
	where completeness is disabled, the search engine will interpret a
	search containing space characters as a word proximity search.
       
boolean
	This directive enables or disables first-in-field indexing.
	The value of the boolean should be 0
	(disable) or 1. 
       
boolean
	This directive enables or disables alwaysmatches indexing.
	The value of the boolean should be 0
	(disable) or 1. 
       
filenameThis is the filename of the character map to be used for this index for field type. See Section 2, “Charmap Files” for details.
filenameSpecifies the filename with ICU tokenization and normalization rules. See Section 3, “ICU Chain Files” for details. Using icuchain for a field type is an alternative to charmap. It does not make sense to define both icuchain and charmap for the same field type.
Example 10.1. Field types
     Following are three excerpts of the standard
     tab/default.idx configuration file. Notice
     that the index and sort
     are grouping directives, which bind all other following directives
     to them:
     
     # Traditional word index
     # Used if completeness is 'incomplete field' (@attr 6=1) and
     # structure is word/phrase/word-list/free-form-text/document-text
     index w
     completeness 0
     position 1
     alwaysmatches 1
     firstinfield 1
     charmap string.chr
     ...
     # Null map index (no mapping at all)
     # Used if structure=key (@attr 4=3)
     index 0
     completeness 0
     position 1
     charmap @
     ...
     # Sort register
     sort s
     completeness 1
     charmap string.chr