The RDF element used in the SBML format for referring to external entities is `<rdf:Description>`, with a `<rdf:Bag>` element inside of it containing one or more `<rdf:li>` elements. The following template illustrates the structure:
<rdf:Description rdf:about="#meta id">
HISTORY
<RELATION_ELEMENT>
<rdf:Bag>
<rdf:li rdf:resource="resource URI" />
...
</rdf:Bag>
</RELATION_ELEMENT>
...
</rdf:Description>
In the template above, the placeholder meta id stands for the element's meta identifier, which is a field available on all SBML components derived from the SBase base object class. The dotted portions are optional, and the ellipses ... are placeholders for zero or more elements of the same form as the immediately preceding element.