The INDEX feature is certainly covered in the Philips-Sony Red Book definition. This publication needs to be cited a lot more in the article, at exact section numbers. CD players (at least mine do) implement this by using the "->>" jump button. Play will jump to the next index point, or failing that, to the next track. Only the tracks can be accessed in random order. Commercial CDs rarely contain INDEX blocks.184.108.40.206 (talk) 00:06, 16 March 2017 (UTC)
Frames and frames
"however, it is rare to find a CD player that displays or can access this feature, except occasionally in pro audio equipment, usually for radio broadcasting."
All my normal, non pro audio CD-Players (Sony) are displaying indices just fine. They cannot access them, though. That's the rare feature here.
"Additional songs, such as "hidden tracks", usually have index 2 or 3."
I think I have four CD with these annoying "hidden tracks". They do not have a additional index information. That's why at least I would refrain from using "usually" here.
See my comment above re INDEX. There must be a two second silence before track 1. It supposedly stops hidden material before then. Track 1 typically starts at sector 150 up to 182. The commencement of continuous play begins at the block of track 1. Bonus material can appear anywhere after the start block (track 1). When a player reads a CD there is just one long audio PCM data stream, which it plays continuously until the last block on the CD, or until the user interrupts it. The time accuracy of a track beginning is in quantums of 1/75 secs (=one whole sector). Numbered song tracks are simply defined by a start block (sector) number. Jumping to a track merely causes the reader to jump to that sector. The is no "END" block or track length defined within the lead-in TOC. The gaps between real tracks are also unnumbered tracks and the INDEX number is 0. CD players will often count backwards (just in a blink) when playing the gaps. The jump button will jump to the next non-zero INDEX. An INDEX number to actual data is >=220.127.116.11.253 (talk) 00:15, 16 March 2017 (UTC)