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.
<!ELEMENT custom-meta %custom-meta-model; >
The following, in order:
... <book-meta> ... <custom-meta-group> <custom-meta> <meta-name>acidfree</meta-name> <meta-value>yes</meta-value> </custom-meta> <custom-meta> <meta-name>price</meta-name> <meta-value>US $28.50</meta-value> </custom-meta> <custom-meta> <meta-name>miscinfo</meta-name> <meta-value>CDs included, Windows XP required; 1GB processor, 512 MB RAM recommended</meta-value> </custom-meta> </custom-meta-group> ... </book-meta> ...