title: Input mask jquery : letter or number
body: <p>In <a href="http://robinherbots.github.io/Inputmask/index.html" rel="nofollow noreferrer">jquery input mask</a>,
  We can specify number and letter. How to get the format where user can input letter or number,</p>
  
  <p>A = Letter,
  9 = number.</p>
  
  <p>I need a mask like this <code>AA - (A or 9)(A  or 9) - 99</code>, </p>
  
  <p>For example, it can be <code>AA-99-99</code></p>
  
  <p>and in another case it can be <code>AA-A9-99</code>, or</p>
  
  <p><code>AA-AA-99</code>, </p>
  
  <p>and so on. I have tried a lot, not suitable.</p>
  
  <p>Please advise.</p>