These descriptions provided here are rather basic and unsophisticated ones.

This is a slide show with 20 seconds per slide

duct: the stroke of the pen
bole (bow or lobe): a rounded part of a character, as in a or b or d
ascender: the upward stroke of a character as in b, l, h
descender: the downward stroke of a character, as in p, but note that such a stroke in y or g might be designated the tail
character: basically a letter
minim: the vertical strokes in m (3 minims), n and u (2 minims) and i (one minim)
suspension: a general contraction at the end of a word
superscript: a character written above the horizontal line of the other characters in a word
initial: the position at the beginning of a word
medial: the position in the middle of a word
final: the position at the end of a word
ligature: is a join between two characters, as between s and t, s and h, s and c, for examples
e caudata or tagged e: is an e with something like a cedilla on it which represents the syncope of the Latin dipthong -ae-; it was used in the twelfth century, but died out by the thirteenth century, leaving only residual e to represent dipthong -ae-
whipped ascenders: feature in the late twelfth century; the upper levels of the ascenders are whipped back down the ascender to form a sort of decoration
majuscule: a hand in which all the characters are the same size regardless of whether they are upper case or lower case or have ascenders or descenders or tails(diagrammatically they can be said to be produced between two lines, although that is a simplification)
minuscule: hands that have different levels for upper and lower case, for ascenders and descenders and tails (and so can, by simplification, be said to be written between four lines)

deletions in texts:

descriptions of mss

Some residual characters:
Signa (sing. signum): these are the crosses at the foot of Anglo-Saxon diplomas against the names of the 'witnesses' and sometimes called the subscriptions.
Diploma: what is loosely called the Anglo-Saxon charter, a formal document which is a dispositive instrument, giving bookland or privileges, which is mainly written in Latin, but with a boundary clause in the vernacular (Old English) and with these diagnostic, constituent clauses: a proem or preamble or arenga of solemn nature; an anathema to assure the benefaction; and the signa or subscriptions at the foot. The notification of the diploma was conveyed by an instruction, the writ which was compiled in the vernacular (OE).
To be completed