When you define a domain, you can optionally indicate that the domain has a superdomain. If a domain has a superdomain, domain attributes are inherited from that superdomain following certain rules. This section describes how a subdomain inherits attributes from its superdomain.
The following attributes of superdomains are always inherited by their subdomains, or by columns defined on them. These attributes cannot be changed at the subdomain level:
•Column Width (see the Note below)
A domain constraint defined for a superdomain is also executed for the subdomains.
The following attributes are only inherited if they have been defined at the superdomain level. If they have the empty value (NULL) at the superdomain level, you can still set them to a value at the subdomain level:
The following attributes are inherited, but can always be overruled at the subdomain level:
•Generate Unique Values
Allowed Values, Alternative Input Formats, and Comments defined for a superdomain are not inherited by subdomains.