Cataloguing information for software objects serves two purposes - 1) to supply material from which a searchable index may be constructed, and 2) to supply information needed by the user to select/reject search hits and to obtain and use selected software. The field names and definitions used for cataloguing in a particular library are described in the data model used by that library. For example, for document libraries, the CSTR project [26] has adopted RFC1357 [14] as its data model.