say unpack 'aaaaa@0aa', 'ABCDEFGH';   # prints ABCDEAB

##</code><code>##

say unpack 'aa(aaa@0)aa', 'ABCDEFGH';  # prints ABCDECD

##</code><code>##

say unpack 'aa(aaa@)aa', 'ABCDEFGH';  # prints ABCDEDE
say unpack 'aa(aaa@1)aa', 'ABCDEFGH'; # prints ABCDEDE

##</code><code>##

say unpack '(C/xa@)3', "\003\003\003abcdef"; # prints 'bcd'

##</code><code>##

say unpack 'aa.', 'ABCDEFGH';  # prints AB2
say unpack 'aaaa.', 'ABCDEFGH';  # prints ABCD4


##</code><code>##

say unpack 'aa./xaa', 'ABCDEFGH';  # prints ABEF

##</code><code>##

say unpack 'aa.aa', 'ABCDEFGH';  # prints AB2CD
say unpack 'a(a.a)a', 'ABCDEFGH';  # prints AB1CD
say unpack 'a(a.*a)a', 'ABCDEFGH';  # prints AB2CD

##</code><code>##

say unpack 'aa(aa).*/Xaa', 'ABCDEFGH';  # prints ABCDAB
say unpack 'aa(aa.*/Xaa)', 'ABCDEFGH';  # prints ABCDAB