/usr/share/cluster/relaxng/fence.rng.head is in fence-agents 4.0.25-2ubuntu1.
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 | <!-- Autogenerated fence definitions -->
<define name="FENCEDEVICEOPTIONS">
<optional>
<choice>
<!-- begin specific fence devices -->
<!-- begin auto-generated device definitions -->
|