there are two basic types of grain files included here:

*.szd - grain size distribution files, currently
	0m010.szd single size - 0.01 micron only
	0m100.szd single size - 0.1 micron
	1m000.szd single size - 1 micron 
	ism.szd interstellar nrm distribution
	orion.szd modified to reproduce orion ratio of total to selective extinction

*.rfi - grain refractive index distributions
	ac1-amcarb.rfi - amorphous carbon
	be1-amcarb.rfi - amorphous carbon
	draine-gra.rfi - graphite
	graphite.rfi - graphite
	grey.rfi - grey grain
	silicate.rfi - silicate
	vacuum.rfi - vacuum

These were developed by Peter van Hoof in collaboration with Peter G. Martin
in support of the "new" distributed grains in cloudy.