default

exactly one subelement is required 

Specifies that a CMP field belongs to the default hierarchical fetch group, which means it is fetched any time the bean is loaded from a database. Enables prefetching of a CMR field. 

level

exactly one subelement is required 

Specifies the level number of a hierarchical fetch group. 

named-group

exactly one subelement is required 

Specifies the name of an independent fetch group. 

none

exactly one subelement is required 

Specifies that this field or relationship is placed into its own individual fetch group, which means it is loaded from a database the first time it is accessed in this transaction.