title: jqueryUI datepicker and allowing non-dates?
body: <p>How would I use the jqueryUI "datepicker" if I want my input field to allow non-dates (or invalid dates)?</p>
  
  <p>I have a server-side script which can handle a normal date as input, or an asterisk to mean "latest date available" (amongst a few other special codes).<br>
  It would be nice to have a popup datepicker in my HTML form, but only when needed.<br>
  How can I use the jqueryUI datepicker to choose a specific date (for example, by clicking on a datepicker icon), while also allowing the user to enter one of our special codes as a "fake date"?  </p>
  
  <p>Thanks!</p>