title: Basics of referencing a xsd schema from another schema
body: <p>We are writing a new xsd schema that will be based upon and reference another schema (that is an industry de facto standard for GPS data called GPX).  Our schema will be used in validating documents generated by our clients, and in testing.  I need to better understand how to reference the base schema from our new schema, especially given that our systems cannot be expected to have an Internet connection.  </p>
  
  <p>My understanding is that references to xsd documents at some other server are typically there so that a developer can retrieve the document during development but during system run-time validation one would be wise to have a local copy of a schema since it would not be prudent to hang production simply because the remote server was unreachable.  Is this correct?</p>
  
  <p>So then if that's the case, does xsd expect me to both reference the remote base xsd schema, but also the name and location of some <strong><em>local</em></strong> copy of the schema?  Or is such a reference not needed in my new schema file?  Hope that makes sense.  Thanks. </p>