Oracle Error Message
PLS-00648: type of supertype attribute “string” can not be a subtype or reference to a subtype in this release
Reason for the Error
User tried to complete a type, Tsub as a subtype of another type, Tsuper where Tsuper contained an attribute of type Tsub or of type REF to Tsub. This is an implementation restriction.
Solution
Change the design of code to not use any type with attribute whose type is of subtype or REF to subtype.