The content of an <indexterm> element is used to produce an index entry in the generated index. You can nest indexterm elements to create multi-level indexes. The content is not output as part of the topic content, only as part of the index.
An <indexterm> element (with no start or end attribute specified) is interpreted as a point reference that will contribute the number of the current page to an index entry whose contents is the content of the indexterm. All indexterms with the same content are "merged" to form a single index entry in the resulting index, and all contributed page numbers are included in that index entry.
In the case of nested indexterms, the indexterms with no indexterm children (i.e., the "leaves") each contribute a page number to the generated index; the ancestral indexterm elements for each leaf indexterm provide the higher levels for the multilevel entry.
An indexterm that occurs in a topic prolog is interpreted as a point reference to the title of the topic. Likewise, an indexterm that occurs in <topicmeta> inside of a <topicref> is interpreted as a point reference to the title of the referenced topic.
It is an error if an indexterm containing no indexterm children contains both an index-see and an index-see-also. (Note: index-see and index-see-also elements within indexterms that do contain indexterm children are ignored.) In the case of this error condition, an implementation may (but need not) give an error message, and may (but need not) recover by treating all such index-see elements as index-see-also elements.
The start and end attribute on indexterm can be used in cases where one wants to index an extended discussion that may continue over a number of pages. The start of a range is indicated by an indexterm with a start attribute. The end of a range is indicated with an indexterm with an end attribute whose value matches that of the start attribute on the start-of-range indexterm. Such markup contributes to the generated index a page range covering all pages in the index range.
The end-of-range indexterm should have no content of its own; if it contains content, that content is ignored. There is no reason for the end-of-range indexterm to have any indexterm ancestors; however, an implementation should be able to handle an end-of-range indexterm that is nested within one or more indexterms.
The start and end attributes are defined as CDATA, though it is recommended that the values should not contain any whitespace characters (e.g., space or tab) or control characters. Matching of start and end attributes is done as a character-by-character comparison with all characters significant and no case folding occurring. The start and end attributes are ignored if they occur on an indexterm element that has child indexterm elements.
When index ranges with the same identifier overlap, the widest range applies, and end ranges are matched with start ranges by last-in-first-out. In other words, the ranges are interpreted as nested rather than overlapping with the highest-level container taking precedence over narrower contained ranges.
As defined above, there is no such thing as an index range start that isn't terminated by either a matching end or some maximum scope. There can, however, be unmatched index range end indications; these should be ignored.
Doctype | Content model |
---|---|
topic (base), map (base), classifyMap, learningAssessment, learningBookmap, learningContent, learningMap, learningOverview, learningPlan, learningSummary | ( text data or data or data-about or foreign or unknown or keyword or term or indexterm or index-base or index-see or index-see-also or index-sort-as) (any number) |
topic (technical content), map (technical content), concept, ditabase, glossary, glossentry, glossgroup, reference, task, bookmap | ( text data or data or data-about or foreign or unknown or keyword or apiname or option or parmname or cmdname or msgnum or varname or wintitle or term or abbreviated-form or indexterm or index-base or index-see or index-see-also or index-sort-as) (any number) |
subjectScheme | ( text data or data or data-about or foreign or unknown or keyword or term or indexterm or index-base) (any number) |
machineryTask | ( text data or data or data-about or foreign or unknown or keyword or wintitle or term or indexterm or index-base or index-see or index-see-also or index-sort-as) (any number) |
<p><indexterm>databases</indexterm>Databases are used to ...</p>
<concept id="db"> <title>About databases</title> <prolog> <metadata> <keywords><indexterm>databases</indexterm></keywords> </metadata> </prolog> <body><!-- content... --></body> </concept>
<topicref href="aboutdatabases.dita"> <topicmeta> <keywords><indexterm>databases</indexterm></keywords> </topicmeta> <!-- other topicref elements --> </topicref>
<indexterm>cheese <indexterm>sheeps milk <indexterm>pecorino</indexterm> </indexterm> <indexterm>goats milk <indexterm>chevre</indexterm> </indexterm> </indexterm>
<indexterm>cheese <indexterm>sheeps milk <indexterm>pecorino</indexterm> </indexterm> </indexterm> <indexterm>cheese <indexterm>goats milk <indexterm>chevre</indexterm> </indexterm> </indexterm>
<indexterm start="cheese">Cheese</indexterm> <!-- ... additional content --> <indexterm end="cheese"/>
<indexterm>cheese <indexterm>sheeps milk <indexterm start="level-3-pecorino">pecorino</indexterm> </indexterm> </indexterm> <!-- ... additional content ... --> <indexterm end="level-3-pecorino"/>
There are three locations that may declare a range - the body of a topic, the prolog of a topic, and a map.
<topic id="accounting"> <title>Accounting regulations</title> <body> <p>Be ethical in your accounting.</p> <p><indexterm start="acctrules">Rules</indexterm>Remember to do all of the following: ...</p> <!-- ...pages worth of rules... --> <p><indexterm end="acctrules"/>Failure to comply will get you audited.</p> </body> <!-- Potential sub-topics --> </topic>
<topic id="accounting"> <title>Accounting rugulations</title> <prolog> <metadata> <keywords><indexterm start="acct">Accounting</indexterm></keywords> </metadata> </prolog> <!-- Body and sub-topics --> </topic>
<topicref href="acct.dita"> <topicref href="procedures.dita"/> <topicref href="forms.dita"/> </topicref>
<topicref href="acct.dita"> <topicmeta> <keywords> <indexterm start="acct">Accounting</indexterm> <indexterm end="acct"/> <indexterm start="govt">Government forms</indexterm> </keywords> </topicmeta> <!-- Nested topicref elements --> </topicref> <topicref href="taxfiling.dita"> <topicmeta> <keywords> <indexterm end="govt"/> </keywords> </topicmeta> </topicref>
Name | Description | Data Type | Default Value | Required? |
---|---|---|---|---|
start | Specifies that an index entry is positioned at the beginning of a range. See the description of <indexterm> for more information. | CDATA | #IMPLIED | No |
end | Specifies that an index entry is positioned at the end of a range; value matches the start attribute on another indexterm. See the description of <indexterm> for more information. | CDATA | #IMPLIED | No |
keyref | Keyref provides a redirectable reference based on a key defined within a map. See The keyref attribute for information on using this attribute. | CDATA | #IMPLIED | No |
univ-atts attribute group (includes select-atts, id-atts, and localization-atts groups) | A set of related attributes, described in univ-atts attribute group | |||
global-atts attribute group (xtrf, xtrc) | A set of related attributes, described in global-atts attribute group | |||
class | A common attribute described in Other common DITA attributes |
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OASIS DITA Version 1.2 -- OASIS Standard, 1 December 2010
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