Lens Warehouse omits the MetaDataVersion and so provides only one current version. Importers should create a warning if a ODM file with more than one MetaDataVersion is about to be imported.
In ODM the elements StudyEventRef, FormRef, ItemGroupRef and ItemRef have an OrderNumber. The OrderNumbers provide an ordering of the reference targets (StudyEventDef, FormDef, ...) for use whenever a list of such targets is presented to a user. They do not imply anything about event scheduling, time ordering, or data correctness.
Lens Warehouse doesn't support OrderNumbers and instead uses the Name of the reference targets to provide an ordering for user facing lists.