Today, a seal is used to protect files sent by customers to BGC from tampering. On the 1st of April 2008, BGC launched HMAC as a new seal generation algorithm for tamper protection. In connection with HMAC being made available, one of the existing seal generation algorithms, MAA, will be phased out and the customers that currently use MAA will need to change methods.
This page provides more information about this change.
HMAC are in operation since 1 April 2008 and MAA will cease to function on 31 March 2009.