DSS2 — Join Federation Execution

The introductory text says, “The returned joined federate designator shall be
unique for the lifetime of the federation execution.” However, during a restore
operation, when the Initiate Federate Restore + service is invoked at a federate,
one of the supplied arguments is a joined federate designator, with the result that
the Initiate Federate Restore + service could cause a joined federate’s designator
to change from the value supplied by the Join Federation Execution service. This
means that while a restore is in progress at one or more federates, it is possible
that two different federates could have the same joined federate designator, one
federate having the designator that was supplied to it by the Join Federation
Execution service and one federate having the designator that was supplied to it by
the Initiate Federate Restore + service. Therefore, the introductory text of the
Join Federation Execution service should be amended to say that “The returned
joined federate designator shall be unique for the lifetime of the federation
execution, as long as a restore is not in progress at any federate.”

Add the text suggested in the issue statement.