title: Which REST operation (GET, PUT, or POST) for validating information?
body: <p>My users enter a few information fields in an iOS app.
  This information must be validated on my server, which has a RESTful API.
  After validation the UI of the iOS app changes to indicate the result.</p>
  
  <p>Neither GET, PUT, or POST seem to be appropriate, because I'm not getting a resource, and neither is a resource created or updated.</p>
  
  <p>What is the best fitting REST operation to implement this validation?</p>