The semantic for t is: "Timestamp of the last change in one of the attribute(s) representing the value of the data or in the q attribute. For the different CDCs, t applies to the following data attributes:"
The table shows various CDC attributes to which t applies, but in no case does the table indicate a q to which t applies. Whether the table is an inclusive list or an exclusive list, and thus whether t applies to q or not, is left to the individual server and client developers to determine. A client should not be left to guess on receiving stVal, q and t whether t applies to stVal or to q.
Remove the words: "or in the q attribute".
It is intended that t changes both with the value as well as with q. As stated that can not be changed since it would be a backwards compatibility issue.
And with the Autogenerated Version of IEC 61850-7-3 in the future, this is as well explicitly stated.
So no Change is needed.
05 Dec 13
I agree with Christoph, the intention was, that t changes as well when q changes.
Either add q in the table or enhance the text as follow:
For the different CDCs, t applies ADDITIONALLY to the following data attributes:
That would be a MAJOR interop issue removing q from the definition. q change always (ed1 included) led to changing t.
05 Dec 13
In my opinion, the intention was, that t changes as well when q changes. So it might be required to include it in the tables.