CMS announces that it will perform maintenance in the CMS data center on December 20, 2012. The maintenance window will begin at 10:00 PM ET on Thursday, December 20, 2012. CMS estimates that the maintenance will be complete by 11:00 PM ET same day on Thursday, December 20, 2012. The HETS 270/271 system will be unavailable during this period. Attempts to open a connection to the HETS 270/271 application will result in errors.