> Instead, it was to support "note" and "point" commands. Atari believed people would use files as a database, and with the sector chaining, it was impossible to jump around in a file without reading it linearly. So a program could "note" its position in a file (sector and offset) and then return there later with the point command. This is where verifying that the file number in the user-supplied sector number matched the entry used when opening the file came in. Without that number, there would be no verification that a "point" would end up in the right file.

Interesting to hear this terminology used in the context of 8-bit Atari computers. The terms NOTE and POINT come from IBM mainframes, where there are OS/360 macros by those names. NOTE essentially does an fgetpos and POINT an fsetpos