/etc/selinux/mls/contexts/ is in selinux-policy-mls 2:2.20110726-3.
This file is owned by root:root, with mode 0o755.
..
/etc/selinux/mls/contexts/customizable_types
/etc/selinux/mls/contexts/dbus_contexts
/etc/selinux/mls/contexts/default_contexts
/etc/selinux/mls/contexts/default_type
/etc/selinux/mls/contexts/failsafe_context
/etc/selinux/mls/contexts/files/
/etc/selinux/mls/contexts/files/file_contexts.subs_dist
/etc/selinux/mls/contexts/files/media
/etc/selinux/mls/contexts/initrc_context
/etc/selinux/mls/contexts/removable_context
/etc/selinux/mls/contexts/securetty_types
/etc/selinux/mls/contexts/sepgsql_contexts
/etc/selinux/mls/contexts/userhelper_context
/etc/selinux/mls/contexts/users/
/etc/selinux/mls/contexts/users/guest_u
/etc/selinux/mls/contexts/users/root
/etc/selinux/mls/contexts/users/staff_u
/etc/selinux/mls/contexts/users/unconfined_u
/etc/selinux/mls/contexts/users/user_u
/etc/selinux/mls/contexts/users/xguest_u
/etc/selinux/mls/contexts/x_contexts