See PRB: SEEK Finds Old and New Data With Optimistic Buffering mskb #Q190496. It's old bug that MS didn't bother to fix.

>Hi
>
>SET NEAR OFF
>SET MULTILOCKS ON
>CREATE CURSOR customer (cust_id c(20))
>INSERT INTO (ALIAS()) VALUES ('AAAAA')
>INSERT INTO (ALIAS()) VALUES ('BBBBB')
>INSERT INTO (ALIAS()) VALUES ('CCCCC')
>INDEX ON cust_id TAG IXcust_id
>=CURSORSETPROP('Buffering',5)
>* =CURSORSETPROP('Buffering',4) && also have bug
>TABLEUPDATE(.T.)
>? SEEK('AAAAA'),RECNO(),cust_id
>REPLACE cust_id WITH '11111'
>? SEEK('AAAAA'),RECNO(),cust_id
>
>We can see that it finds the value old and firm on the successive record.
>
>I uses many, many table buffering cursors.
>
>It put me on much evil state, I need revision any index uses, explicit or implict ( rushmore OPTIMIZATION: SELECT,REPLACE,CALCULATE,LOOKUP,.... all!).
>
>Fabio