P*CH activation

HI.

Pardon the cross-posting, I'm not sure where this question really belongs.

I've been trying to wrap my head around how PDTCH/PACCH/PTCCH activation works. In osmo-bts-sysmo/oml.c there is pdtch_sapis[] which defines what got to be activated both in DL and UL directions. Right now it's PDTCH (UL & DL), PTCCH (DL) and PRACH. Note that PACCH (DL) and PTCCH (UL) are commented out.

Yet I see code dealing with PACCH in osmo-pcu and corresponding log messages.

So the question is - how does this works? The PACCH seems to be used so it's somehow activated but apparently not the same way as PDTCH.