PDME — Behavior of Lockable operations is not defined

Source: PDME-RTF, derived from issue 2485

Summary:
In section 3.3.8, the following Note appears: "Note ­ It is up to the inheriting classes to include the locking or checks for
locks on dependent objects. For example, it is up to the Document classes to define what happens to DocumentRevisions when the
Document object is locked."
But in fact, nothing in DocumentManagement defines this, nor does anything in ProductStructure define the effects of locking on
PartRevisions, nor does anything in ManufacturingImplementation define the effects of locking on ProcessRevisions, etc. The PDM
Enablers should define the common interoperable locking behaviors on each class that inherits from Lockable, and where necessary
at least say that locking behavior is implementation-defined.