If a simple type with enumeration restrictions is further restricted without changing the enumeration list, the sub-type attempts to re-generate the parent type enumerations resulting in an error.
1. Enumerations should only be generated for the owner datatype.
2. Need to figure out what the facets on the restricted type should be: e.g., are the enumeration values listed in the base type still acceptable. See section 3.14.6/Derivation Valid (Restriction Simple)/1.3.2