If the validation numbers are not null, and they match, then the sites agree on
a new validation number to be used the next time, and the session continues.
If the validation numbers are not null, and they don't match, then the session
is brought to an abrupt end, and a bulletin is sent to the Postmaster to notify
site managers of the 'bad validation number'. To correct this, someone at your
site must contact (by phone, usually) someone at the other site, and one of you
must change your validation number to match the other's. Once the fields have
been edited to match, then you can re-schedule a task to transmit the messages.
The VALIDATION NUMBER (field #1.6) is used as an extra security precaution
to confirm that the site really is who it says it is.
After the connection has been established, the validation numbers are compared.
If the validation numbers are null, then the security precaution is not active,
and the session continues.