| POSC Specifications Version 2.2 | Epicentre Logical Data Model |
Object_alias has as its natural keys (K): effective_date, expiry_date, and ref_naming_system. Not included in the natural keys are: identifier, and the (in each subtype) reference to the object. Although both of these are mandatory. Identifier should be part of the natural keys. Probably, also, should be the reference to the object.
The following subtypes of object_alias did not include the object they are an alias for in their uniqueness clause. This has been rectified. The identifier attribute in the alias subtypes is NOT included as part of the uniqueness clause as this would mean that for a given ref_naming_system, at a given period of time, there could be more than one possible value of an alias for an object. So, for example, a well could have several API numbers at the same time. This is not the behavior needed.
Modified objects:
coordinate_system_alias.si (Unique rule)
ellipsoid_alias.si (Unique rule)
geodetic_datum_alias.si (Unique rule)
typical_material_alias.si (Unique rule)
ref_code_alias.si (Unique rule)