To support random chapter selection, next and previous operations from the user remote control unit, the DVD player reads information from a data structure named Video Title Set Part-Of-Title Search (VTS_PTT_SRPT). This data structure is defined at byte offset 200 of VTSI_MAT (sector 1).

The contents of the following data structure can be obtained by reading from the file position at 2048 bytes (1 sector * 2,048 bytes/sector) relative to the beginning of the VTS_01_0.IFO file. Each chapter (Part-Of-Title or PTT) is identified by a unique program chain PGC and the associated program number PGN with the specified PGC as following.

Video Title Set Part-Of-Title Search (VTS_PTT_SRPT)
Offset	Bytes	Description	Value
0	2	Number of title units (TTUs) in the VTS	1
2	2	Padding bytes
4	4	Address of last byte (length of table-1)	23
One or more title units following
8	4	Starting byte of PTT for title 1	12
One or more Part-Of-Titles (PTTs) following
12	2	Program Chain number (PGC)	1
14	2	Program number within the PGC	1
16	2	Program Chain number (PGC)	1
18	2	Program number within the PGC	2
20	2	Program Chain number (PGC)	1
22	2	Program number within the PGC	3

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