note LanX I understand your problem, for my understanding "dynamically scoped" should mean <c>local</c>ized such that the sum at the end shouldn't be 4=1+1+1+1 but 1+7777+666+55. but if you read the docs differently <tt> <pre> Capture group contents are dynamically scoped and available to you outside the pattern until the end of the enclosing block or until the next successful match, whichever comes first. </pre></tt> you can see that the next match within the recursion sets $1 to another value. At least that's ATM my understanding of the designers intention. > a branch to a point within the same block no, no tail-head optimization in Perl! I will try to run some experiments tomorrow. UPDATE1: hmm, w/o recursion and with different strings it works like localized: <c> DB<112> sub tst2 { 'a' =~ /(\w)/; $1. tst(). $1 } => 0 DB<113> sub tst { 'b' =~ /(\w)/; $1} => 0 DB<114> 'c' =~ /(\w)/; print $1. tst2(). $1 => 1 cabac </c> UPDATE2 you're right there is a bug in how recursive functions are handled: <c> DB<123> sub delchar { $x =~ s/(\w)// ? $1 . delchar() . $1 : "x" } => 0 DB<124> $x='abc' => "abc" DB<125> delchar() => "cccxccc" </c> in contrast explicitly different functions: <c> DB<138> sub del1 { $x =~ s/(\w)// ? $1 . del2() . $1 : "x" } => 0 DB<139> sub del2 { $x =~ s/(\w)// ? $1 . del3() . $1 : "x" } => 0 DB<140> sub del3 { $x =~ s/(\w)// ? $1 . del4() . $1 : "x" } => 0 DB<141> sub del4 { $x =~ s/(\w)// ? $1 . del5() . $1 : "x" } => 0 DB<142> $x='abc'; del1() => "abcxcba" </c> Perl 5.10 UPDATE3 the following shows that $1 is static per function, maybe they where implemented like closures. <c> DB<111> sub del2 { $x =~ s/(\w)// ? $1 . del1() . $1 : "-" } => 0 DB<112> sub del1 { $x =~ s/(\w)// ? $1 . del2() . $1 : "-" } => 0 DB<113> $x='abcd'; del1() => "cdcd-dcdc" </c>  <div class="pmsig"><div class="pmsig-708738"> Cheers Rolf </div></div> 1009091 1009091