 Vellum comes from the Latin word vitulinum which means "of calf"/ "made from calf".For modern parchment makers and calligraphers, and apparently often in the past, the terms parchment and vellum are used based on the different degrees of quality, preparation and thickness, and not according to which animal the skin came from, and because of this, the more neutral term "membrane" is often used by modern academics, especially where the animal has not been established by testing.Because they are books, pre-modern manuscripts are best described using bibliographic rather than archival standards.