Getcontentlength & GetContentType

What should I respond if a client asks for the properties Getcontentlength or GetContentType on a collection?
The spec states:
"The getcontentlength property MUST be defined on any
   DAV compliant resource that returns the Content-Length header in
   response to a GET."

But it doesn't say, if the value a supposed to be the same as if I perform a 'Get' on that url. The collection itself doesn't normally have a content, so does this mean that if the collection have a default page. That it should return the values of that page? Or if the server is set to send a generated HTML page listing the children, should the values be text/html and the size of that page?

Or have I missed something in the spec?

/Rickard Falk