IMS VDEX allows the exchange and expression of simple machine-readable lists of human language terms, along with information that may assist a human in understanding the meaning of the various terms, i.e. a flat list of values, a hierarchical tree of values, a thesaurus, a taxonomy, a glossary or a dictionary.
VDEX was designed to supplement other IMS specifications and the IEEE LOM standard by giving additional semantic control to tool developers.
For example, it is possible, in some profile types, for terms to be contained within one another and be nested, which is suited to the expression of hierarchical vocabularies.
VDEX also offers some scope for complex vocabularies, assuming the existence of a well-defined application profile (for exchange interoperability).
Some examples are: Identifiers in VDEX data should be persistent, unique, resolvable, transportable and URI-compliant.