title: How do I resolve which locale to use if the client requests "en", but I only have country specific locales?
body: <p>I'm working with a SOAP integration standard that includes localized vocabulary files.  Basically, any text field can have a language/country code included with it.</p>
  
  <pre><code>&lt;RoleName&gt;
      &lt;lang&gt;en&lt;/lang&gt;
      &lt;text&gt;Administrator&lt;/text&gt;
  &lt;/RoleName&gt;
  </code></pre>
  
  <p>One of our partners is sending us only "en", however the default vocabulary files that are distributed with the standard only include  "en-US", "en-CA", and "en-GB".</p>
  
  <p>My gut is that I should be rejecting their requests because they aren't sending the accepted language codes as defined by the spec, but they're insisting that we should be able to resolve "en" since it's a valid code and we have english vocabularies available.</p>
  
  <p>Am I off base on this?  What's the best practice?  Is it expected that given a general language code that we should automatically resolve to a more specific national code if we have it by using our own default or something? </p>