Hi Guys, i'm pretty new to Gearsluts, so please be nice

(I hope this is posted in the right section)
I've recently got a bunch of stems in, and at the start of all the stems the engineer says "(X) stem to remix 20R" where (x) is the insturment/vox/etc ..
Problem is i've no idea what that means
My instinct said it was probably 20% pan right, but all the files are stereo .wavs, and seem to be panned different directions themselves - and it doesn't sound "right" to pan them all right!
There are 8 stems - LV, BGV, strings, AGT, EGT, Keys, drums and Bass, all 16bit, @44.1 kHz, but i'm totally lost as to what the teminology "to remix 20R" is.
Thanks in advance,
Tom