On 7 May 2001, Microsoft introduced Visio Enterprise Network Tools (VENT), an add-on for Visio 2002 scheduled for release on 1 July 2001, and Visio Network Center, a subscription-based web service for IT professionals who use Microsoft Visio for computer network diagramming.[23] VENT was discontinued on 1 July 2002 because of very low customer demand.[24]