rid Reference to an Identifier

Value of the identifier of an associated element; used for linking related elements (for example, <term> to a <def>, <bio> to a <contrib>).
OPTIONAL on elements: <milestone-end>, <milestone-start>
Value Meaning
An identifier (IDREF) Points to the existing identifier.
Restriction @rid is an optional attribute; there is no default.
REQUIRED on element: <index-term-range-end>
Value Meaning
An identifier (IDREF) Points to the existing identifier.
Restriction @rid is required; it must be provided if the element is used.
OPTIONAL on many elements; click for list and usage
Value Meaning
One or more identifiers (IDREFS) Points to one or more existing identifiers.
Restriction @rid is an optional attribute; there is no default.
Tagged Samples
Pointing to a figure
...  
<p>Allocation of tags to individual molecules is outlined in
 <xref ref-type="fig" rid="F2" alt="figure two">Fig.&#x00A0;2</xref>.
 First, the complete repertoire of tags ...</p> 
<fig id="F2">...</fig>
...
Pointing to bibliographic citations
...  
<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>
...
Contributor pointing to an author note
...  
<contrib contrib-type="author" corresp="no" rid="fn1">
 <name><surname>Mullin</surname>
  <given-names>David A.</given-names></name>
</contrib>
...