12. A non-transitory computer-readable medium carrying computer-executable instructions implementing a browser-based classification editor having a first tier functionality and a second tier functionality, wherein when executed by a computer said first tier functionality and said second tier functionality operate within a single classification page of a browser application running on said computer, wherein said first tier functionality is operable to enable a user of said computer to create and modify a plurality of groups; select and associate attributes with each of said plurality of groups; and define and modify conditions for each of said plurality of groups, wherein each of said plurality of groups comprises objects having one or more associated attributes that meet at least one of said conditions; and wherein said second tier functionality is operable to enable said user to create and manipulate expressions comprising said plurality of groups.
12. A non-transitory computer-readable medium carrying computer-executable instructions implementing a browser-based classification editor having a first tier functionality and a second tier functionality, wherein when executed by a computer said first tier functionality and said second tier functionality operate within a single classification page of a browser application running on said computer, wherein said first tier functionality is operable to enable a user of said computer to create and modify a plurality of groups; select and associate attributes with each of said plurality of groups; and define and modify conditions for each of said plurality of groups, wherein each of said plurality of groups comprises objects having one or more associated attributes that meet at least one of said conditions; and wherein said second tier functionality is operable to enable said user to create and manipulate expressions comprising said plurality of groups. 14. The computer-readable medium of claim 12 , wherein said first tier functionality is operable to display a default expression comprising names of at least two groups and a relationship between said at least two groups.