#2 Combining of Message Types

[Seth Rothenberg]

If Engine supports labelling of messages as having a certain type,
it should be possible to have multiple types that are treated
as a set of types.

For example,
Admissions and Discharges and Outpatient Registrations may be all
different types, but there may be a translation and interface
that needs to process all these types, in strict FIFO order.

Refer to "Queuing controls" requirement.