1. A method, comprising: establishing an extensible list of attributes of various information resources in an information system, wherein each information resource can be classified according to one or more attributes; establishing an extensible list of values for the attributes in the extensible list of attributes, wherein each value is associated in the list with its corresponding attribute; and selecting a first set of one or more of the values from the extensible list of values to be a first set of target criteria to designate a subset of the information resources.