Grid computing
X.509 ACs and PMIs are used today in Grids (see Grid computing), to assign privileges to users, and to carry the privileges around the Grid. In the most popular Grid privilege management system today, called VOMS, user privileges, in the shape of VO memberships and roles, are placed inside an X.509 AC by the VOMS server, signed by the VOMS server, and then embedded in the user's X.509 proxy certificate for carrying around the Grid.