Some DTDs and schemas allow for metadata above and beyond that which can be specified by the NCBI Book DTD and NCBI Collection DTDs. This element is used to capture metadata elements that have not been defined explicitly in the models for either of these DTDs, 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 DTD previously used by NCBI included elements for <price>, <acidfree>, and <miscinfo>, none of which have counterparts in the NCBI Book DTD and NCBI Collection DTDs; 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-wrap> <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-wrap> ... </book-meta> ...