3
Terms and definitions
[intro.defs]
3.40
[defns.regex.primary.equivalence.class]
primary equivalence class
⟨regular expression⟩
set of one or more
character
s (
[defns.
character]
) which share the same primary sort key: that is the sort key weighting that depends only upon character shape, and not accents, case, or locale specific tailorings