1.7.3 Introduction to Information Levels
The set, query, and selective enumerate patterns of methods that use information levels to communicate the set of object attributes that are to be set or queried in the method request. Information levels are enumerations.
Future versions of the protocol will introduce new information levels that allow a client to specify an information level that is not supported by the server. This situation can occur when a later client communicates with an earlier server.<6>