function validate(field) {
  var valid = "0123456789"
  var ok = "yes";
  var temp;
    for (var i=0; i<field.value.length; i++) {
    temp = "" + field.value.substring(i, i+1);
      if (valid.indexOf(temp) == "-1") ok = "no";
    }
      if (ok == "no") {
      alert("Sorry - can you go back to the 'Type Style choice' \rand enter the ref No. of your chosen typestyle ");
      field.value=""
      }
}