Callable RDO is a program interface that you must use when Oracle Rdb
    does not support a preprocessor for your program language.  You can also
    use this interface when you want to perform Rdb data definition tasks or
    dynamic data manipulation tasks in BASIC, C, COBOL, FORTRAN, or Pascal
    programs.

    When you use the Callable RDO program interface, your program
    communictes with Oracle Rdb using a callable function, RDB$INTERPRET.
    Unlike preprocessor interfaces, the Callable RDO interface performs in
    an interpretive manner.

    The Rdb statements you use in your pgoram are string literals.  When the
    program executes, the statements are passed to Oracle Rdb in the calls
    to RDB$INTERPRET.  The interactive Rdb interface, RDO, then interprets
    and executes them.

    You call the RDB$INTERPRET function as you would call a VMS Run-Time
    Library routine.  In the calling sequence, you pass both Rdb statements
    and host language variables that cuase values from teh database to be
    retrieved or updated.  The call to RDB$INTERPRET returns a status value
    that indicates the success or failure of the statements.  If the call
    was successful, RDB$INTERPRET also returns retrieved database values to
    the appropriate program variables.

    For more information, refer to the Guide to Using RDO, RDBPRE, and
    RDML.