Schematic definition of the various regions of M 31 discussed in Sect. 2. The different colors show the points used in the derivation of Figs. 21–24. The inner (100 arcsec) region of the CB is indicated in orange, the outer region perpendicular to the bar in magenta. The bar region outside the CB is represented in brown, the B/P region in green, and the disk in cyan. North is to the top, east to the left.