MOTM

I've been -gradually- getting started on the DIY side of things and  
have relied considerably on the
(no longer available, but I saved a copy,) Synth Tech Tutorial/
Resource page for tool suggestions, and I have been wondering
about Paul's recommendation: "A stable, regulated power supply for  
testing. I STRONGLY suggest buying a linear supply.
It needs to be a "triple output" (+5, +12, -12). I like the Elpac  
Model WM220-1."

Question, why/how is a +12/-12 PS acceptable when MOTM (format)  
modules are rated for +15/-15?

tia,
Jack