Alabaster - A white horse color. These can have points of a different color and may have shading of light grey or cream with a mostly white base. This term is not used with real horses.
from Special Run Legacy Gift Set II
Alabaster, grey shading, darker points except mane and tail, stockings
Alabaster, cream shading and points, mottled face, grey muzzle
Alabaster, grey shading, flaxen, stripe and white muzzle