Annex E (informative) Conformance with UAX #31 [uaxid]

E.5 R4 Equivalent normalized identifiers [uaxid.eqn]

UAX #31 requires that implementations describe how identifiers are compared and considered equivalent.
C++ requires that identifiers be in Normalization Form C and therefore identifiers that compare the same under NFC are equivalent.
This is described in [lex.name].