How to do A-B looping?

I’m reading the Sansa m240 User Guide, page 4. Under the REPEAT / AB button, it says “Press and hold to enable A-B looping”. There’s no more mention of the “A-B looping” function, not even in chapter 2.

Am I missing something? Can someone please point me to the instruction, or just tell me how to do it. Thanks.

I need to learn how to use this function, e.g. how to set the markers for point A and point B in the song, etc.

it doesnt work like that.

Repeat A is repeat one song over and over, Repeat A-B is repeat all the songs in any given list.