MiataLink AT-F question

I purchased a NA miata with an FM2 kit installed, I've noticed the temp
correction for fuel and/or ignition doesn't seem to be right just
observing the wbo2 and knock in various temperatures... This brought me
to the AT-F and AT-IGN pages on the hand controller.

In all the documentation I've found the AT-F is referred to as a single
value, but on my controler it's presented with two values:

AT-F L=N H=N

What is the default supposed to be for the L=? What is the meaning of
the L= value? I presume the reason I'm not finding any information on
the two value version of AT-F is my firmware must be out of date
relative to the PDF files available on the FM site.

Any input much appreciated.

Cheers,
Vito Caputo