seems to be done in one of those two hashes holding callbacks to handle [doc://...] links

• handlelinks settings
• new handlelinks settings

update

ironically it's the first one

return( "http://perldoc.perl.org/", 'Perl documentation' ) unless $suf
+fix;
my $func= getVars(getNode('perl keyword list setting','setting'));
if( $func->{$suffix} ) {
   "http://perldoc.perl.org/functions/$escsuffix.html"
}
elsif( $suffix =~ /^[\$\@%]/ ) {
   "http://perldoc.perl.org/perlvar.html#$escsuffix"
}
else {
   my ( $page, $anchor ) = split '#', $suffix, 2;
   my ( $uri, $title ) = ( "http://perldoc.perl.org/" );
   $uri .= join '/', map $q->escape( $_ ), split /::/, $page;
   $uri .= '.html';
   if( defined $anchor ) {
       $uri .= '#' . $q->escape( $anchor );
       ( $title = $q->escapeHTML( $q->unescape( $anchor ) ) ) =~ y/-/ 
+/;
   }
   ( $uri, ( $title ) x!! defined $title );
}
[download]

update

a fix might look like (untested)

return( "http://perldoc.perl.org/", 'Perl documentation' ) unless $suf
+fix;

if( $suffix =~ /^[\$\@%]/ ) {
   "http://perldoc.perl.org/perlvar.html#$escsuffix"
}
else {
   my ( $page, $anchor ) = split '#', $suffix, 2;
   my ( $uri, $title ) = ( "http://perldoc.perl.org/" );

   my $func= getVars(getNode('perl keyword list setting','setting'));
   $uri .= "functions/$page" if( $func->{$page} ); # handle functions

   $uri .= join '/', map $q->escape( $_ ), split /::/, $page;
   $uri .= '.html';
   if( defined $anchor ) {
       $uri .= '#' . $q->escape( $anchor );
       ( $title = $q->escapeHTML( $q->unescape( $anchor ) ) ) =~ y/-/ 
+/;
   }
   ( $uri, ( $title ) x!! defined $title );
}
[download]

update

maybe better like this

return( "http://perldoc.perl.org/", 'Perl documentation' ) unless $suf
+fix;

if( $suffix =~ /^[\$\@%]/ ) {
   "http://perldoc.perl.org/perlvar.html#$escsuffix"
}
else {
   my ( $page, $anchor ) = split '#', $suffix, 2;
   my ( $uri, $title ) = ( "http://perldoc.perl.org/" );

   my $func= getVars(getNode('perl keyword list setting','setting'));

   if( $func->{$page} ) {
      # LanX: handle functions
      $uri .= "functions/$page";  # ??? do functions need to escaped?

   } else {
      # LanX: handle core modules and pragmas 
      $uri .= join '/', map $q->escape( $_ ), split /::/, $page;
   }

   $uri .= '.html';
   if( defined $anchor ) {
       $uri .= '#' . $q->escape( $anchor );
       ( $title = $q->escapeHTML( $q->unescape( $anchor ) ) ) =~ y/-/ 
+/;
   }
   ( $uri, ( $title ) x!! defined $title );
}
[download]

update

regarding  $uri .= "functions/$page";  # ??? do functions need to escaped?

none of the functions listed in perl keyword list setting needs to be escaped. even -X works fine

comments???

Is there a test suite?