The primary operational functions of a vocabulary service are:
1) to assign meaning to a given term (i.e. a token that represents a concept)
2) to provide terms related to a queried term
To be useful in a computer information system, these functions must be accessible through machine readable interface.
In
addition, a vocabulary service might provide a variety of maintenance
or stewardship functions, but these might not operate through the same
web interface as the definition and query functions because of access
control issues.
Shared vocabularies require an authoritative registry for reference purposes.