A name to attach to the origins of the manuscript

[Jorge_Stolfi]

Not vellum, Jorge. Parchment 

I recall reading somewhere that the two words once had well-established meaning in English, with "vellum" being specifically calf skin.  But more recently the two terms have become interchangeable in England (while still being distinguished in France, where the name "vellum" came from.) 

If true, that is a bit peculiar, since technical terms usually become more specific with time. (See "planet" which, according to the IAU, now does not include Pluto and is distinct from "dwarf planet" and other obligatorily qualified types of "planet").

The nasty little demon behind my left ear says that it happened because some British "experts" who claimed to distinguish calf from lamb by sight were embarrassed when lab tests became available and revealed their mistakes.  

But I try not to listen to that demon.  Much. It is not good for one's reputation... 

All the best, --stolfi