except
Returns the members of "set_expression1" that are not also in "set_expression2". Duplicates are retained only if the optional keyword "all" is supplied as the third argument.
Syntax
except ( set_expression1 , set_expression2 [ , all ] )
Example
except ( set ( [Camping Equipment] , [Mountaineering Equipment] ) ,
set ( [Camping Equipment] , [Golf Equipment] ) )
Result
Mountaineering Equipment