MDAC 2.5 SDK - ODBC Programmer's Reference
Appendix F: ODBC Cursor Library
If the driver supports this function, the cursor library calls SQLNativeSql in the driver and passes it the SQL statement. For positioned update, positioned delete, and SELECT FOR UPDATE statements, the cursor library modifies the statement before passing it to the driver.
Note The cursor library incorrectly returns SQLSTATE 34000 (Invalid cursor name) if the cursor name is invalid in a positioned update or delete statement that is passed in the InStatementText argument of SQLNativeSql. SQLNativeSql is not intended to return syntax errors, which are returned only upon statement preparation or execution.