Halliday & Matthiessen (2014: 347):
… in the identifying, the criteria tend to conflict. For purposes of simplicity, we will interpret the Token as Medium and the Value as Range in all types, although this does ignore some aspects of the patterning of such clauses in text.
To be clear, this only applies to decoding clauses (Identified/Token, Identifier/Value)
In encoding clauses, there is no Range; the Identifier/Token is Agent, and the Identified/Value is Medium.