Attribute entries are used to actually store metadata. Each attribute in a CDF may have zero or more associated entries. For vAttributes two types of entries are supported: rEntries and zEntries. rEntries describe some property of the corresponding rVariable, and zEntries describe some property of the corresponding zVariable. Note that an entry does not have to exist for each variable in the CDF. For gAttributes only one type of entry is supported and is referred to as a gEntry. The gEntries are independent of anything else in the CDF and have meaning only to the application. Note that gEntries are sometimes referred to simply as ``entries.''