Rekall can be configured to prompt you to verify changes to data in the database. You'll probably not want these set (Rekall assumes that you know what you are doing), but they are useful if you are particularly paranoid about changing your data! Note that they only apply to changes made by forms (and not directly by any scripts).
The three main options concert table inserts, updates and (record) deletion. The available options are not to request verification (this is the default), to always request verification, or to request verification only when more than one record will be affected.
The fourth option only applies if you have any form blocks which do not have the automatic update option set; since automatic update is the default this option is usually not applicable. If the verufy multi-record sync option is set, then any database updates (inserts, updates or deletes) which are made for the data in that block will be verified.