Hi IFixPlanes!
Haha I was in EDDF perhaps 4 days ago I think, memory shot, too much flying, goddam the cloud base was low, a proper 100 to go....minima and see the lights!!
It is interesting the 4th/5th stage difference. My A320 CFM doc simply states the following: The HPTCC controls the HPC 4th stage (Air) (-5A 5th stage).
Acronyms are a real annoyance (on a tangent):
FADEC = ECU + HMU
HMU = FCU in old speak
FCU = MCP in Boeing speak etc.etc. doh!