1992 Volvo 940 Timing

I have the B230F engine.
Regarding timing the enginge my Chilton's repair manual says "Rotate the crankshaft so the notch in the convex crankshaft gear belt guide aligns with the embossed mark on the front cover (12 o'clock position)."
My Haynes manual says "Align all the timing marks on the engine block with the marks on the crankshaft and camshaft sprokets."
Both have drawings of the same engine, but indicate slightly different positions of the crankshaft, idler and camshaft alignment points.
Can you help?