Picasa Android Sample - if modify this to work for gdocs, which attribute to use for requesting a file download?

[Nick Longinow]

Hi - the sample works perfectly, and I've been able to retrofit it for gdocs, which allows me to upload docs using oauth.  This is the right approach for me, as it doesnt require my app to ask users to enter their credentials to my app, just to Google. So far so good.

Now, I want to browse the document list.  Again the picasa sample is perfect, and the code allows me to get a list of the documents, including the name. The picasa sample has etag and title as attributes returned by the get call. 

If I want to now do a download of a document, should I use the 'etag' as the ID, or is there another one I should use?