[Vwdiesel] Piston size stamp and associated markings

[ken1]

I have seen the insides of two (2) vw diesel engines. I have found the where 76.48 is stamped on the piston, the arrow that shows which way the pistons should be facing. I also found two (2) additional markings; one appears as a minus sign or dash and the other appears as a plus sign. What do they mean? I can try for a picture tomorrow, after my batteries are charged in my digi-camera.
What I am trying to determine is: Are the pistons in both engines standard or oversize?
thanks.
ken