Eh, CVC stands for "Validation Rule"!
Okay, that doesn't make a lot of sense, and I imagine it started out as something more reasonable like "Content Validation Constraint" back in the days before the first working draft.
The main thing is that:
- By starting all validation rules with
cvc-
, uniqueness is aided by avoiding a clash between the name and one for another rule. - It acts as a handy clue to the type of rule, as all validation rules start with
cvc-
and only validation rules start withcvc-
. Similarly, all schema representation constraints start withsrc-
exceptschema-reference
.