Hello,
I apologize for the delayed reply. There are numerous ways to do partings. If you choose to use a map then it will discriminate between black and white values of the map to determine which parting particular strands belong to. For example, in a checkers map the white squares will belong to a different parting than black squares.
You may also use strand groups (through Edit Guides modifier) to define which parting/group guides belong to. Hairs will then inherit these partings based on the guides from which they were created. You can also use vertex channels of the distribution mesh to define these groups.
Lastly, as you mentioned, you can use auto-partings which will just measure angles between guides to determine where to split the parting.
Marsel Khadiyev (Software Developer, EPHERE Inc.)