title: Using Regex for a Purchase Order
body: <p>I'm not sure this is even possible</p>
  
  <p>I was given a requirement to match Purchase Order numbers within a filename.
  His requirement is below:</p>
  
  <p><em>I would say a minimum of 4 characters, with no max limit. However there MUST be a string of 3 consecutive LETTERS (minimum) somewhere in this section.</em></p>
  
  <p>123ABC - match
  A123ABC - match
  ABC123 - match
  123XY67 - NO match
  ABC1VJ6K - match</p>
  
  <p>The best I can come up with is [0-9A-Z]{4,}; however, that matches basically ANY 4 characters</p>