This is a feature which allows defining a device with one name, but specifying
its substitution string for <> substitution to be something different. See
"Device Name Substitution" in Tutorial.
Also, Walt is correct in that the "serviceData" message is only intended to
be used by cdevServices, not applications, and so the tags they use are
defined late.
If this is a problem, we could change this behavior. Note that if you do
any type of I/O message ahead of your cdevDirectory operation which causes
the caService to load, then your code will work.
Chip