Committed Read is not enough for fetching BLOB rows...

Hi, I have committed read isolation level between transaction. But in some cases I found that the select queries got error -164:ISAM err: Blob stamp is incorrect. I read the detailed message of this error and I was very surpprised on that. For example I have a transaction using normal cursor for read and an other using update cursor for update the same rows. If I understand well the cursor fetch the rows in two steps. At the first it reads the normal types then the BLOB types. But in committed read it doesn't put any locks on the row. So If the second transaction update the same row, it could change the row between the two step of fetch and it can cause the error -164. Is it true? The solution I suppose using cursor stability isolation...(?) Andor Rozsnyai