This illustration is described in the text. It shows how the PL/SQL datatypes are grouped into categories: scalar, composite, reference, and LOB types. The composite types (record, table, and varray) are described in a subsequent chapter. The reference types (REF CURSOR and REF object_type) are described in a subsequent chapter. The LOB types (BFILE, BLOB, CLOB, and NCLOB) are briefly described in this chapter and fully described in the book "Application Developer's Guide - Large Objects". All other types, such as NUMBER and VARCHAR2, are scalar and are described in this chapter.