I'm using the PC flight schedule to look for flight times, etc.

On there it has an entry for meal. I see various combos of letters here. The following seem reasonably self-explanatory:

LB = lunch/breakfast, though I don't know why that order
DB = dinner breakfast
LS = lunch/snack
LL = ?
M = ?

These are all international routes.

On the domestics, I see the following:
F = ? (seems to indicate meal only if F)
G = ? (on late flights and redyes, so probably means no meal)

Can anyone confirm these?

Is there a better source for meals on given routes?

TIA