rid Reference to an Identifier

Value of the identifier of an associated element; used for internal links of related elements. For example, an <xref> can point to the @id of a figure (<fig>).
REQUIRED on element: <index-term-range-end>
Value Meaning
An identifier (IDREF) Must point to an existing identifier within the standards document.
Restriction This attribute is required; it must be provided if the element is used.
OPTIONAL on many elements; click for list and usage
Value Meaning
An identifier (IDREF) Points to the existing identifier within the standards document.
Restriction This is an optional attribute; there is no default.
OPTIONAL on many elements; click for list and usage
Value Meaning
One or more identifiers (IDREFS) Points to one or more existing identifiers within the standards document.
Restriction This is an optional attribute; there is no default.
Tagged Sample

Cross reference pointing to figure

...
<sec id="s5_1">
 <label>5.1</label>
 <title>Two approaches to addressing accessibility in 
  standards</title>
 ...
 <p><xref ref-type="fig" rid="f1">Figure 1</xref> provides 
  a graphical summary of how this Guide can be used.</p>
 <fig id="f1" orientation="portrait" position="anchor">
  <label>Figure 1</label>
  <caption>
   <title>Two approaches to address accessibility in 
    standards</title>
  </caption>
  <graphic xlink:href="g3658.jpg"/>
 </fig>
 ...
</sec>
...