This is an illustration of the object hierarchy starting with OraField and OraParameter at the same level. At the next level, the following descend from OraField and OraParameter: OraObject, OraRef, OraCollection, OraBlob, OraClob, OraBFile, and value of all other scalar types.

At the third level, OraAttribute descends from OraObject or from OraRef, and element values descend from OraCollection.