Bing just published (and publicized) an extensive list of Advance Operators. What a look into their search technology this offers! For example, here's a description of the advanced operator norelax:
norelax: Only allow search word, phrase or word: in the constraint. Bing implements relaxcount for a 5+ word query by default; that is, the fifth word in a query and subsequent appears do not necessarily appear in results.
Example: cry for you lyrics norelax:September
Remarks The effect of the syntax in this example is to specify that all returned results must contain september. In the absence of the norelax: operator, since there are 5 words in the query, Bing would augment with a relaxcount=+1, that could return documents that do not contain september.