As you may or may not know, the documentation set for Dynamics AX 4.0 is on MSDN. That includes the user and administrator help as well as the developer help.
Let’s say you're looking for AX-only information. You can use the usual MSDN search, but the results may include topics from other products, especially if you search on something like select. In that case, you’ll get a raft of hits including the select function, the select object, the select method, the select keyword in T-SQL – you get the idea. Somewhere on page 200 of your results is the topic that you need.
The good news is that now you can limit your MSDN search to only Dynamics AX topics. The bad news (and isn’t there always some bad news) is that you can’t do it from the MSDN search itself. The new and improved search is on the Dynamics AX Developer Center, right on the home page.
With the advanced search, you can search all the AX help, search the non-developer help and restrict your search based on whether you want to search reference or non-reference topics. Let us know how it works!