Catalog Selection Order for DEFINE

If a catalog is defined in the CATALOG parameter, that catalog is selected to contain the to-be-defined entry.
When a non-VSAM generation data group (GDG) data set is defined, the catalog containing the GDG base is selected to contain the to-be-defined non-VSAM entry.
If no user catalog is specified for the current job step or job, the entry's name is a qualified name, and:
- One or more of its qualifiers is the same as the name or the alias of a catalog, or
- The first qualifier is the same as the name or the alias of a VSAM user catalog,
then the catalog so identified is selected to contain the to-be-defined entry.
If no catalog has been identified, either explicitly or implicitly, VSAM defines an object in the master catalog.