10 Too Many Nested BEGIN SEQUENCE/END Blocks

     Explanation:  Too many nested BEGIN SEQUENCE/END blocks have been
     defined.  The maximum is 16.

     Note: The usual reason this occurs is a LOOP statement within a
     BEGIN SEQUENCE/END structure like the following:

     DO WHILE <condition>
        <statements>...
        BEGIN SEQUENCE
           <statements>...
           LOOP
        END <statements>...
     ENDDO