DDS15 — The DDS Specification should define legal DDS Topic Types

The DDS v1.2 specification does not explicitly define the subset of IDL that can be used to express Topic Types. From the specification, it can be inferred – and all vendor have done so – that a topic type is defined by means of a struct and that the IDL types that cannot be used for the attributes of this struct are Value-Types, Any Types and Object References.

The DDS v1.2 should explicitly state this. Notice the the problem is not solved by the X-Types specification as that introduces a set of types, such as Maps, Optional types, etc. that are not supported by DDS v1.2 implementations.

This is really a critical matter which is trivial to solve. Just state what is implicitly assumed and should be fixed ASAP.