One actually has to look at the OWL or Svante's examples to know what the namespaces are that have to be declared

http://docs.oasis-open.org/ns/office/1.2/meta/pkg# is mentioned in the "declared namespaces" section at the start of part 3
and http://docs.oasis-open.org/ns/office/1.2/meta/odf# is listed in part1 section 1.5
but it would be wise to also mention this in the metadata sections, it is a powerful new feature that deserves extra attention