Chip's CD Media Resource Center:
CD-R (Recordable) 4

CD-R Layout

Again, from Whitworth:

The transition from lead-in to program area must always occur at radius 25 nm [mm] at ATIP time 00 minutes, 00 seconds, 00 frames. Since various linear velocities are used other recording areas must have adjustable ATIP times to satisfy this criteria.

The wobble contains these start times:

• start of lead-in
• start of lead-out
• ATIP start time (start of grooves)
• ATIP step time (outer most recorded grooves)

I'll work on this "CD Layout" section some more...