Meaning of ATIP start of lead in

When reading parameters from different brand of CD recorable disc, I notice
it never have the same ATIP start of lead in value.

For example :

ATIP info from disk:
Indicated writing power: 4
Disk Is not unrestricted
Disk Is not erasable
Disk sub type: Medium Type A, high Beta category (A+) (3)
ATIP start of lead in: -11849 (97:24/01)
ATIP start of lead out: 359847 (79:59/72)
Disk type: Long strategy type (Cyanine, AZO or similar)
Manuf. index: 25
Manufacturer: Taiyo Yuden Company Limited

Here ATIP start of lead in = -11849 LBA or 97:24:01 MSF so size of Lead in is 11849 sectors because
Lead in spread from start (97:24/01) to 00:00:00.

But the standard says that the size of a standard lead in is 9Mb/ 60 seconds/4500 sectors.

So what is true ? Is the Lead in always 4500 sectors sized ? In this case why ATIP start of lead in value
varies from brand to brand ? Does it mean something special ?

ATIP is an acronym for Absolute Time In Pregroove .