Explanation: Ubuntu <%= codename=scope.lookupvar('apt::codename') %> security
Package: *
Pin: release o=Ubuntu,a=<%= codename %>-security
Pin-Priority: 990

Explanation: Ubuntu <%= codename %> updates
Package: *
Pin: release o=Ubuntu,a=<%= codename %>-updates
Pin-Priority: 980

Explanation: Ubuntu <%= codename %>
Package: *
Pin: release o=Ubuntu,a=<%= codename %>
Pin-Priority: 970

Explanation: Ubuntu backports
Package: *
Pin: release a=<%= codename %>-backports
Pin-Priority: 200

Explanation: Ubuntu <%= next_release=scope.lookupvar('apt::next_release') %>
Package: *
Pin: release o=Ubuntu,a=<%= next_release %>
Pin-Priority: 2

Explanation: Ubuntu fallback
Package: *
Pin: release o=Ubuntu
Pin-Priority: -10