Taupe (gray or blue -brown)
Flesh (peachy or pinkish-browns)
T F L
XT1 XF1 XL1
XT2 XF2 XL2
XT3 XF3 XL3
Also some metallic color designations to indicate reflective faux color mixtures: XAU (gold), XAG (silver) and XCU (copper)
For very precise color groupings, use X + the 6 digit/letter code for the exact color, such as XFF0000 for that difficult true red on screen that prints shockingly orange.