The DECLARE_VARIABLE and DEFINE_TYPE clauses have exactly the
    same function. Oracle Rdb decided to rename the clause to clarify
    that its function is to declare host language variables, not to
    define host language types. Note that the DEFINE_TYPE clause
    may still be used; however, Rdb recommends that all new
    applications use the DECLARE_VARIABLE clause in place of the
    DEFINE_TYPE clause. See the help file entry on DECLARE_VARIABLE
    for more information.