^(??{q(.+)})\x{100} \x{100}\x{100} y $& \x{100}\x{100}
^(??{q(.)})\x{100} \x{100}\x{100} y $& \x{100}\x{100}
^(??{chr 0x100})\xbb \x{100}\x{bb} y $& \x{100}\x{bb}
+\x{100}?(??{""})xxx xxx y $& xxx
^(.)(??{"(.)(.)"})(.)$ abcd y $1-$2 a-d
^(.)(??{"(bz+|.)(.)"})(.)$ abcd y $1-$2 a-d
^(.)((??{"(.)(cz+)"})|.) abcd y $1-$2 a-b
(a)(?:(?-1)|(?+1))(b) abb y $1-$2 a-b
(a)(?:(?-1)|(?+1))(b) acb n - -
-(foo)(\R2) foofoo y $1-$2 foo-foo
-(foo)(\R2)(foo)(\R2) foofoofoofoo y $1-$2-$3-$4 foo-foo-foo-foo
-(([abc]+) \R1)(([abc]+) \R1) abc abccba cba y $2-$4 abc-cba
+(foo)(\g-2) foofoo y $1-$2 foo-foo
+(foo)(\g-2)(foo)(\g-2) foofoofoofoo y $1-$2-$3-$4 foo-foo-foo-foo
+(([abc]+) \g-1)(([abc]+) \g{-1}) abc abccba cba y $2-$4 abc-cba
+(a)(b)(c)\g1\g2\g3 abcabc y $1$2$3 abc
+
/(?'n'foo) \k<n>/ ..foo foo.. y $1 foo
/(?'n'foo) \k<n>/ ..foo foo.. y $+{n} foo