phrase needed

[bruce pomerantz]

Dear Web4Libers, 

Hope you take the adage, "The only dumb question is the one unasked" to
heart as I ask: 

In boolean searching, what do you call the search strategy when you
use one or more pairs in parentheses.  An example: 

(Cats or Dogs) (Mice or Birds) 

Thanks for not laughing. 

Bruce Pomerantz
On Sabbatical in Cincinnati