code: function (chrs, buffer, pos, strict, opts) {
                          var isValid = opts.regex.val1.test(chrs);
                          if (!strict && !isValid) {
                              if (chrs.charAt(1) == opts.separator || "-./".indexOf(chrs.charAt(1)) != -1) {
                                  isValid = opts.regex.val1.test("0" + chrs.charAt(0));
                                  if (isValid) {
                                      buffer[pos - 1] = "0";
                                      return { "pos": pos, "c": chrs.charAt(0) };
                                  }
                              }
                          }
                          return isValid;
                      }
docs: val1 ~ day or month