Type of Cross-Reference
Type of element that is the target of the cross-reference (for example, “figure”, “author-note”, “bibliographic-reference”). The values may be used for type-specific processing or validation.
The <xref> element may be used to reference anything that has an @id attribute. This single element takes the place of the many named types of references (such as figure references, table references, and footnote references) that are common in many journal tag sets. This attribute preserves the information from such tag sets concerning the type of element to which the cross-reference is pointing.
Used on Element: <xref>
|Text, numbers, or special characters||The element to which the reference points, for example, “fig” to indicate that the reference points to a figure (<fig>).|
|Restriction||@ref-type is an optional attribute; there is no default.|
Although designed to accept any text as its value, potential values for this attribute might include:
Bibliographic reference (typically to a <ref> element, but it may point to a <element-citation> or <mixed-citation> if there are multiple citations inside the <ref> element).
Textbox or sidebar
Chemical structure (to a <chem-struct> or <chem-struct-wrap> element)
Figure or group of figures (to a <fig> or <fig-group> element)
List or list item (to a <list> or <list-item> element; also, possibly to a <def-list> or <def-item> element)
Table or group of tables (to a <table-wrap> or <table-wrap-group> element)
... <p>... The third nucleotide (CG<bold>A</bold>) at codon 529, which is a specific nucleotide of <italic>M. tuberculosis</italic> (<xref ref-type="bibr" rid="B8">8</xref>, <xref ref-type="bibr" rid="B11">11</xref>), was not clearly determined ...</p> ...