/search/X? urls and default search options (adjacency, and ...)

[Sara Amato <samato@xxxxxxxxxx>]

In constructing urls to do Adv. Keyword searches, we came across the 
following oddity:

If we make a simple URL such as:

http://phebe.bowdoin.edu/search/X?imperialism+india

the system defaults to an OR search, searching imperialism OR india. 
This is NOT the default when searching directly in the webpac.  We 
discovered if we added even one of the other parameters on, such as 
SORT, e.g.

http://phebe.bowdoin.edu/search/X?imperialism+india&SORT=D

the system did the "right thing" and first tried and adjacency search, 
and failing that moved onto an "and" search.

While this isn't really a problem, we can of course add the SORT or 
other values on to the url, it is sort of a mystery to us.  We had been 
teaching faculty and librarians that they could construct URLs to search 
the catalog using the simple /search/indextag?search+words structure.

Anyone have any thoughts on this and why it works this way?