if ($l2 =~ s/..../..../) {
   # $x and $y munging code
   # and substitution back into $l2
}
##</code><code>##

else {
   warn "houston, we have a problem: $l2 ";
}

##</code><code>##

s!(\d\d)\:(\d\d)\:(\d\d),(\d\d\d) --> (\d\d)\:(\d\d)\:(\d\d),(\d\d\d)!sprintf("%s;%s;%s;%02.0f %s;%s;%s;%02.0f",$1,$2,$3,$4/10,$5,$6,$7,$8/10)!e