David,
Yes you are clear enough. And I can confirm that the encoding is needed and correct, and using the syntax i men tioned above, it works fine when I test it. It does not do a literal search using AT%26T, but rather brings up values for AT&T.
Are you trying to query a SharePoint list or Project Data?
Prasanna Adavi,PMP,MCTS,MCITP,MCT TWitter: @prasannaadavi Blog: http://www.prasannaadavi.com