J.P. Instruments EDM 930 Primary Pilots Guide - Manual (Page 25)

For Your Safe Flight Page 20
Section 5 - LeanFind
The EDM supports two methods of leaning; ROP (Rich Of Peak) and
LOP (Lean Of Peak). Note: on power-up, the unit defaults to
Rich Of Peak mode, but is easily changed to Lean Of Peak mode. During
traditional Rich Of Peak leaning, you’ll finalize the mixture to about 20°
to 80° rich of peak (depending on engine operating requirements).
However, with the advent of closely balanced injectors (such as GAMI),
it is possible to set the mixture lean of peak—thus saving fuel and
running the engine cooler. Both Rich Of Peak and Lean Of Peak
processes are described in detail in this manual.
Upon reaching cruise configuration, use the LeanFind mode to identify
the correct cylinder to reach peak EGT (for Rich Of Peak this is the
FIRST to peak, for Lean Of Peak this is the LAST to peak). To change
from one method to the other, right after activating LeanFind, hold
STEP and LF and the other method will be momentarily shown: ROP
(Rich Of Peak) or LOP (Lean Of Peak). Release buttons after the other
method appears.