>When you tell the TABLEUPDATE() function to force the changes I believe that VFP generates an UPDATE statement that uses the key fields only. If you think about it, without behavior like this, the force parameter would never have any effect.

It appears that the TABLEUPDATE statement has the power to override the WHERE clause settings...

Well, it never made sense to me why one would use modified fields in the WHERE clause anyway, especially if the want more recent changes to be overridden. This behavior would explain it.