This is RT-11 Partitioning, but if I remember correctly it?s even fancier than that.  The
data in the disk images is accessible from RT-11 as RT-11 partitions, and from a modern
computer as disk images on an ISO-9660 CD.  The person that put these together is a very
*LONGTIME* RT-11 person.
Zane
  On Mar 31, 2020, at 8:11 AM, Johnny Billquist <bqt
at softjar.se> wrote:
 
 If you have that CD hooked up to a (simulated) PDP-11 running RT-11, I could imagine that
we are talking about the RT-11 partitioning of large MSCP drives.
 
  Johnny