When looking for round carbide inserts for a shell mill I purchased I see letter notations such as RDHW, RCMA & RDHX. Can't seem to find what this notation means. Looks like something to do with geometry.
The shell mill in question is an Interstate RFA-500-RD12-150 shell mill
a search turns up this page from Dorian:

says for +15' rake RD style cutters
RDHW Gage Insert 120400
I.C. .472
Thick .1875
HoleDia. .220
geometry RDHW-1204MO-EN

So I have only one source for these insert (dorian)?