Because the routing function of the intermediaries in the I-cloud can use several meta data attributes for routing messages the PMode.Reliability.Correlation parameter will be defined (partly) by the I-cloud. The expression will need to contain all meta data attributes that the [actual] I-cloud will use for routing. Endpoint can then further narrow the usage of a sequence by adding other XPath expressions.
I would like to leave the definition of these common XPath expression out of scope and something determined out of band.
Sander