UMLR — Justification for messages on differnent sides of a gate being identical is not clear.

In the description of matching on gates...
"Gates are matched by name, with a formal Gate matched with an actual Gate having the same name, and with an inner CombinedFragment Gate matched with an outer CombinedFragment Gate having the same name.

The Messages for matched Gates must correspond. Messages correspond if they have identical name, messageSort, and signature property values, as well as being in the same direction."

Matching the Gates makes sense. However, requiring the message details to match invariantly seems to be overly restrictive. For example, a message in the same direction, and messageSort, but perhaps with covariant/contravariant matching of parameters should be acceptable