id

Identifier

Unique identifier of an element; allows element to be cross-referenced. Value must be unique across a document, not just for an element type.

Remarks

The ID and IDREF attribute values constitute a primitive reference mechanism for XML. For example, when an @id attribute has been used on a <glyph-data> element, that identifier can be referenced by an IDREF-style attribute on a <glyph-ref> element, so that the full glyph data can be pointed to and need not be repeated every time the character is used.

An identifier string is typically 1-32 characters in length and must start with a letter of the alphabet. (It is an XML rule that identifiers may not start with a digit.)

Attribute Values

In Element

<target>
Value Meaning
An identifier (ID) A unique identifier for the element.
Restriction: This attribute must be specified if the element is used.

In Elements

<abbrev>, <ack>, <address>, <aff>, <aff-alternatives>, <alt-text>, <app>, <app-group>, <array>, <article-title>, <attrib>, <author-comment>, <bio>, <boxed-text>, <caption>, <chem-struct>, <chem-struct-wrap>, <col>, <colgroup>, <collab>, <contrib>, <contrib-group>, <custom-meta>, <def>, <def-item>, <def-list>, <disp-formula>, <disp-formula-group>, <disp-quote>, <element-citation>, <ext-link>, <fig>, <fig-group>, <fn>, <fn-group>, <funding-source>, <glossary>, <glyph-data>, <graphic>, <inline-formula>, <inline-graphic>, <inline-supplementary-material>, <institution>, <iso-meta>, <leading-org>, <list>, <list-item>, <long-desc>, <media>, <milestone-end>, <milestone-start>, <mixed-citation>, <mml:math>, <named-content>, <nat-meta>, <non-normative-example>, <non-normative-note>, <notes>, <p>, <person-group>, <preformat>, <ref>, <ref-list>, <reg-meta>, <related-article>, <related-object>, <sec>, <sig>, <sig-block>, <source>, <speech>, <statement>, <supplementary-material>, <table>, <table-wrap>, <table-wrap-group>, <tbody>, <tbx:termEntry>, <td>, <term>, <term-display>, <term-sec>, <tfoot>, <th>, <thead>, <title>, <title-wrap>, <tr>, <trans-source>, <trans-title>, <verse-group>, <wi-number>, <xref>
Value Meaning
An identifier (ID) A unique identifier for the element.
Restriction: This attribute may be specified if the element is used.