The entries describe the Q channel data to be recorded in the lead-in (TOC) of the CD. I attach a sample from a program I wrote to read CD. It shows the TOC lead-in for my disc.
Session = which session of the CD is being described.
Point = If set to 01 to 99 we are describing one of the tracks. In this case PMin, PSec and PFrame are set to the start time of the track (minutes, seconds, frames).
Point = If set to A0, PMin indicates first track of this session. If set to A1, PMin indicates last track of this session. In these 2 cases, PSec and PFrame are set to zero. If Point is set to A2, PMin, PSec and PFrame are set to the start time of leadout for this sessin.
AMin, ASec and AFrame are set to 0 during lead-in. The Zero field is always set to 0 in lead-in.
TrackNo = 0 means we are in track 0 which is lead-in track.
Control and ADR are 4 bits each and make up the 'mode' byte. If Control is 0 then the track being described is Audio. If Control is 4 then the track being described is ROM data. ADR is describing the mode of the leadin Q channel which is almost always set to 1. It can be set to 5 if the CD is multisession.
Most of the information above can be found in:
Red Book (audio CD spec)
Yellow Book (ROM CD spec)
Orange Book (multisession CD spec)
My guess for ALBA (absolute logical block address) when set to -150 indicates lead-in.
I can not understand the PLBA entries.