Custom Metadata

Some tag sets allow for metadata above and beyond that which can be specified by the Book Tag Set and Collection Tag Sets. This element is used to capture metadata elements that have not been defined explicitly in the models for either of these Tag Sets, so that the intellectual content will not be lost.


The <custom-meta> element allows for an infinite variety of name/value pairs, with few constraints on the length or content of the value. This element will probably be used for special cases, product-related material, or other unusual metadata. For example, the Tag Set previously used by NCBI included elements for <acidfree> and <miscinfo>, neither of which has a counterpart in the Book Tag Set and Collection Tag Sets. The content of these elements, however, may be preserved by using the <custom-meta> element.


id Identifier
specific-use Specific Use
xlink:actuate Actuating the Link
xlink:href Href (Linking Mechanism)
xlink:role Role of the Link
xlink:show Showing the Link
xlink:title Title of the Link
xlink:type Type of Link
xmlns:xlink XLink Namespace Declaration

Related Elements

The element <custom-meta-group> is a grouping element that holds one or more <custom-meta> elements. Each <custom-meta> element contains a name/value pair, <meta-name> and <meta-value> respectively, which name and provide a value for a single metadata field.

Content Model

<!ELEMENT  custom-meta  %custom-meta-model;                          >

Expanded Content Model

(meta-name, meta-value)


The following, in order:

This element may be contained in:



<meta-value>US $28.50</meta-value>
<meta-value>CDs included, Windows XP required; 1GB processor, 
512 MB RAM recommended</meta-value>