Creating form templates

What do the regex patterns look like and what flavour of regex is expected? I tried the following and they all passed, but I wasn’t expecting them to:

  • 2[6-9][0-1][0-9][0-3][0-9] with an entry of 180918;
  • /2[6-9][0-1][0-9][0-3][0-9]/ with an entry of 180918;
  • /2[6-9][0-1][0-9][0-3][0-9]/ with an entry of 12;