Within each basic tooth form there are a number of different pitches, inch and metric, and some other subtleties, ergo this quote from a drive distributor's site:
Common pitches and profiles include XL (.200"), L (.375"), MXL (.080"), H (.500") HTD (3mm, 5mm, and 8mm), Powerhouse® (2mm, 3mm, 5mm, 8mm, and 14mm), T2.5, T5, T10, AT5, AT10, and Powerhouse MX® (8mm and 14mm).
I'm guessing that maybe all the conventional (trapezoid tooth) motorsports belts are probably L pitch?
Just curious, I run all low tech V belts on my car except of course the timing belt which is "OEM" and- I think - a metric trapezoidal belt.
Al Seim