An ID which is used within a TLS service to identify which service
packets are associated with as they traverse the TLS trunks.
Each Tls service, virtual port, configured needs an Id assigned
to it. Each packet received on this virtual port, subscriber port
and channel, is stamped with this value for its trip around a TLS
trunk. These tags are assigned by the EMS and must be unique on a
given TLS trunk. This value is a 10-bit number providing a range
of 1k. Values 1..15 are reserved. Value 0 is used for TLS
services that are not provisioned over a TLS trunk. These trunkless
TLS services perform only local switching.