zen% perl -wle 'print "miss" if "aa" !~ /^a{,3}$/'
  miss
  zen% perl -wle 'print "match" if "aa" =~ /^a{0,3}$/'
  match
  zen% perl -wle 'print "match" if "a{,3}" =~ /^a{,3}$/'
  match
  zen%