regcomp regexp compilation ck_null s| S
match pattern match (m//) ck_match d/
qr pattern quote (qr//) ck_match s/
-subst substitution (s///) ck_null dis/ S
+subst substitution (s///) ck_match dis/ S
substcont substitution iterator ck_null dis|
-trans transliteration (tr///) ck_null is" S
+trans transliteration (tr///) ck_match is" S
# Lvalue operators.
# sassign is special-cased for op class