Type of Cross-Reference
Type of element that is the target of the cross-reference (for example: a Figure (“fig”), an Author Note (“author-notes”), or a Bibliographic Reference (“bibr”)). The values may be used, for example, 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 can preserve the information from such tag sets concerning the type of element to which the cross-reference is pointing.
Used on Element: <xref>
|award||Points to the description of or identifier of a grant or award (<award-id>), possibly to an entire awards group (<award-group>)|
|bibr||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)|
|bio||Biography (typically of a contributor)|
|boxed-text||Textbox or sidebar|
|chem||Chemical structure (to a <chem-struct> or <chem-struct-wrap> element)|
|fig||Figure or group of figures (to a <fig> or <fig-group> element)|
|list||List or list item (to a <list> or <list-item> element; also, possibly to a <def-list> or <def-item> element)|
|other||None of the items listed|
|table||Table or group of tables (to a <table-wrap> or <table-wrap-group> element)|
|Restriction||@ref-type is an optional attribute; there is no default.|
... <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> ...