What is an Oracle INDEXTYPE

An INDEXTYPE is  an object that specifies the routines that manage a domain (application-specific) index . Use the CREATE INDEXTYPE statement to create an indextype, which is. Indextypes reside in the same namespace as tables, views, and other schema objects. This statement binds the indextype name to an implementation type, which in turn specifies and refers to user-defined index functions and procedures that implement the indextype. Create any INDEXTYPE is a privilege in RESOURCE role.