METS objects are built by RLG based on descriptive data from contributors. Some contributors may choose to use controlled
vocabularies in some elements. RLG encourages the use of controlled vocabularies, but does not require it, or specify any
particular controlled vocabulary.
METS documents which conform to this profile may use all of the same extension schema
as the "ECHO Dep Generic METS Profile for Preservation and Digital Repository
Interoperability" parent profile.