Additionally, Matteo Rizzo's post say the following about the alpha channel of specular maps under labpbr1.0:
alpha: subsurface scatter on foliage and gems, light emission on other materials, inverted so that blocks not utilizing this can have solid alpha
Sooo... the shaderpacks that implement LabPBR1.0 are supposed to arbitrarily switch from subsurface scattering to light emission when it's not foliage and gems? Does this hold true for LabPBR1.2? Would like to tinker with subsurface scatterring for quartz ore and blocks... but that is definately not folliage and i'm guessing it doesn't count as gems either.
EDIT... seems to be a bit more complicated than that above quote makes it seem. Also holy crap look at those emerald glitter in the moon light. Preeettty!