function f1() {
  local var=$0;
  f2
}

function f2() {
  typeset -n -u ref=var;
  echo "$0: ref=$ref";
  local var=$0;
  echo "$0: ref=$ref";
  f3
  echo "$0: ref=$ref";
}

function f3() {
  echo "$0: ref=$ref";
  local var=$0;
  echo "$0: ref=$ref";
  f4
  echo "$0: ref=$ref";
}

function f4() {
  echo "$0: ref=$ref";
}

f1;