DBStructDef :: IsA - Is structure of passed type
The function returns, whether the complex data type has exactly the type passed in sTypeName . The function returns true , when types are identical.
When calling the function with an invalid type definition or when the type definition does not refer to a complex data type, the function throws an exception.
Return value: Return value ( logical )
The function returns YES when the question was answered positively. Otherwise it returns NO .