This tag has the effect of requesting a verification of all fields that have the potential of having been changed. It is, thus, different from vinstantiated in that past fields that may be hanging around due to change or what not, will not be verified. This may be the more efficient of the two to use, if it does what is needed.
The ignore directive will remove all fields from error that may have changed in the current form. Note that it will not effect errors due to verifications.