Thanks Hilmar for following up on this query. REST and w/o REST it should work the same, wouldn't it? The index is set for id.

>>Without ALL it randomly misses to REPLACE the logical value with .T., though the percentage is very low 2% say. But as the records are not registered=.t. they get deleted next time round (my logic) messing up the whole data integrity.
>>
>>

SEEK m.id
>>REPLACE dbf.registered WITH .T. WHILE dbf.id = m.id

>> ...
>
>I was forgetting: the logical keyword in this case would be REST instead of ALL. That means, "from this point on, until the end of the file (or until the WHILE condition fails)".