Casing

Noun

 * 1) That which encloses or encases.
 * Some people like to split the casing of a sausage before cooking so it doesn't split, others don't.
 * 1)  The collective states of upper and lower case letters.
 * The replacement string should have the same casing as the matched text.

Derived terms

 * sausage casing

Verb
casing