Not all data relations in RDF represent straight binary connections between resource and object value. Some data values, such as measurement, have both a value and additional information that determines how you treat that value. In the following RDF/XML:
<pstcn:lastEdited>18</pstcn:lastEdited>
the statement is ambiguous because we don’t know exactly what
18
means. Is it 18 days? Months?
Hours? Did a person identified by the number 18 edit it?
To represent more structured data, you can include the additional information directly in the value:
<pstcn:lastEdited>18 days</pstcn:lastEdit>
However, this type of intelligent data then requires that systems know enough to split the value from its qualifier, and this goes beyond what should be required of RDF parsers and processors. Instead, you could define a second vocabulary element to capture the qualifier, such as: