UML14 — UML RTF 1.4 Issue: Guard condition in collaborations poorly named.

[p 125, notation] predecessor guard-condition
sequence-expression return-value := message-name
argument-list

The descriptions after this imply that "predecessor" and "guard
condition" are the same:

[p 125, notation] The meaning is that the Message is not
enabled until all of the communications whose sequence
numbers appear in the list have occurred (once the
communication has occurred the guard remains
satisfied). Therefore, the guard condition represents a
synchronization of threads.

It's confusing the have two names for the same thing. I
thought on first glance that some bracketed notation as in
state machine were supported at this position in the label, but
that is in the recurrence part of sequence expressions.

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