NCBI Book DTD and NCBI Collection DTD Tag Library version 2.3

id

Identifier

Definition

Indicates the unique identifier for an associated element, so that the element’s content may be cross-referenced. IDs must be unique inside their document (not just within their element type), and the XML parser enforces this.

Usage

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.

Remarks

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.)

Authoring Note: At present, not all elements with a id attribute are actually of type ID and can be cross-referenced. To ensure backwards compatibility with prior versions of other Tag Sets created using the base Suite (i.e., the Journal Publishing Tag Set and Journal Archiving Tag Set versions up to and including 2.3), the following elements cannot be referenced using the ID/IDREF mechanism:

These elements use a CDATA (data character) attribute type, which does not possess the same cross-reference capability as an ID attribute type found on such elements as <fn>.

Attribute Values

In Elements

<def-list> Definition List; <list> List; <list-item> List Item; <tex-math> Tex Math Equation
Value Meaning
Text, numbers, or special characters Unique identifier for the element within its document. Parsers cannot check uniqueness or matching.
Restriction: This attribute may be specified if the element is used.

In Elements

<overline-start> Overline Start
<underline-start> Underline Start
Value Meaning
An XML identifier (ID) A unique identifier for the element. An XML parser can verify that an IDREF-style attribute pointing to one of these is pointing to a valid ID.
Restriction: This attribute must be specified if the element is used.

In Elements

<abbrev> Abbreviation or Acronym; <abstract> Abstract; <ack> Acknowledgments; <address> Address/Contact Information; <aff> Affiliation; <alt-text> Alternate Title Text (For a Figure, Etc.); <app> Appendix; <app-group> Appendix Matter; <array> Array (Simple Tabular Array); <article-title> Article Title; <attrib> Attribution; <author-comment> Author Comment; <author-notes> Author Note Group; <bio> Biography; <book-part> Book Part; <book-title> Book Title; <boxed-text> Boxed Text; <caption> Caption of a Figure, Table, Etc.; <chem-struct> Chemical Structure (Display); <chem-struct-wrapper> Chemical Structure Wrapper; <citation> Citation; <col> Table Column (XHTML table model); <colgroup> Table Column Group (XHTML table model); <collab> Collaborative (Group) Author; <collection> Collection; <collection-member> Collection Member; <contract-num> Contract Number; <contract-sponsor> Contract Sponsor; <contrib> Contributor; <contrib-group> Contributor Group; <corresp> Correspondence Information; <custom-meta> Custom Metadata; <def> Definition List: Definition; <def-item> Definition List: Definition Item; <disp-formula> Formula, Display; <disp-quote> Quote, Displayed; <ext-link> External Link; <fig> Figure; <fig-group> Figure Group; <fn> Footnote; <fn-group> Footnote Group; <gloss-group> Glossary Group; <glossary> Glossary Elements List; <glyph-data> Glyph Data for a Private Character; <grant-num> Grant Number; <grant-sponsor> Grant Sponsor; <graphic> Graphic; <inline-formula> Formula, Inline; <inline-graphic> Graphic, Inline; <inline-supplementary-material> Inline Supplementary Material; <institution> Institution Name: in an Address; <kwd> Keyword; <kwd-group> Keyword Group; <long-desc> Long Description; <map-group> Image Map; <media> Media Object; <milestone-end> Milestone End; <milestone-start> Milestone Start; <mml:math> Math (MathML 2.0 Tag Set); <named-content> Named Special (Subject) Content; <nlm-citation> NLM Citation Model; <note> Note in a Reference List; <notes> Notes; <p> Paragraph; <person-group> Person Group for a Cited Publication; <preformat> Preformatted Text; <ref> Reference Item; <ref-list> Reference List (Bibliographic); <related-article> Related Article Information; <related-object> Related Object Information; <sec> Section; <sig-block> Signature Block; <source> Source; <speech> Speech; <statement> Statement, Formal; <supplementary-material> Supplementary Material; <table> Table (XHTML table model); <table-wrap> Table Wrapper; <table-wrap-group> Table Wrapper Group; <target> Target of an Internal Link; <tbody> Table Body (XHTML table model); <td> Table Data Cell (XHTML table model); <term> Definition List: Term; <tfoot> Table Footer (XHTML table model); <th> Table Header Cell (XHTML table model); <thead> Table Header (XHTML table model); <title> Title; <tr> Table Row (XHTML table model); <trans-abstract> Translated Abstract; <trans-source> Translated Source; <trans-subtitle> Translated Subtitle; <trans-title> Translated Title; <verse-group> Verse Form for Poetry; <xref> X(cross) Reference
Value Meaning
An XML identifier (ID) A unique identifier for the element. An XML parser can verify that an IDREF-style attribute pointing to one of these is pointing to a valid ID.
Restriction: This attribute may be specified if the element is used.

NCBI Book DTD and NCBI Collection DTD Tag Library version 2.3

Version of March 2007