The following built-in segment attributes are referenced during external messaging:
Glb.CCS
Glb.CorStatus
Glb.DestEnv
Glb.DestHost
Glb.Destination
Glb.DestNoForm
Glb.DestXnID
Glb.HTimeOut
Glb.HubStatus
Glb.HubTimeOut
Glb.Origin
Glb.OriginEnv
Glb.OriginHost
Glb.OriginIspec
Glb.OriginPtn
Glb.OriginXnID
Glb.Param
Glb.PrevIspec
Glb.Query
Glb.Self
Glb.SelfEnv
Glb.SelfHost
Glb.SelfXnID
Glb.StnHost
Glb.TwoPC