"the 7912 is an ST 7912CV which according to the DS is a TO220 with pins 1=gnd, 2= in and 3= out."
Kind of tells you I DID RTFM
My gripe is with common parts such as the 78 or 79xx series devices I would expect them to be drop in replacements for each other, but if you are going to draw a circuit diagram use the pin designator not numbers. The use of G, I ,O on those circuit diags rather than 1,2,3 would of been much more use to a beginner or anyone else as far as I am concerned.