ICR, IMR and IFR used to be meaningful, but they’ve kind of become somewhat obsolete. We still see IMR (Li-Manganese) and even IFR (LiFePO4), but ICR (Li-Cobalt) has slithered away, with the advent of hybrid chemistries, which encompass more than a few chemical combinations.
I prefer ‘high drain’ with ‘moderate drain’ when choosing a cell for a particular application.
It used to be (2012) that you could have 5A+ continuous current and lower capacity, or you could have <5A and higher capacity, but these new hybrid chemistries have turned that on its head.
Always match the cell to the load your device will require, so you need to know your ‘load’.
Chris
ETA:
I = lithium
C = cobalt
M = manganese
N = nickel
F = iron
R = round/cylindrical