Unlike most other PDP-11 software `xxdp` was not sold to Mentec.
By now, ownership of `xxdp` software is in the hands of HP.

PDP-11 customers were not required to sign a license agreement for `xxdp`,
the software was provided with the system or brought to the customer site
by a Field Service representative.

Bottom line is that there is certainly copyright on the `xxdp` software,
but it appears that there is no license restricting its use.
