Old guy from the West Virginia/Western Pennsylvania tradition of geetars and such once informed me that Mother Maybelle's style of picking, using Thumbpick with the fingernails of the other fingers like that was called, "Frailing".

These kinds of terms can be colloquial and also limited as to use by region, though.

There is also a banjo style known as Frailing, pretty much the same idea but with or without the thumb pick.


--Mac