/etc/apparmor.d/abstractions/ubuntu-xterm is in apparmor 2.12-4ubuntu5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 | # vim:syntax=apparmor
#
# for allowing access to xterm
#
  #include <abstractions/consoles>
  /dev/ptmx rw,
  /{,var/}run/utmp r,
  /etc/X11/app-defaults/XTerm r,
  # do not use ux or Ux here. Use at a minimum ix
  /usr/bin/xterm ix,
 |