Mark,
thanks for your answer.
Your Phyton RT-11 code looks good to me, I'll rely on it at least as
reference.
Joerg
I've written (bad?) Python code to manipulate
RT-11 filesystems, including on TU58 tape images:
https://github.com/NF6X/pyRT11
I don't remember which specific documentation I referred to when I wrote this code,
but it may well have been something like this manual:
http://bitsavers.trailing-edge.com/pdf/dec/pdp11/rt11/v5.6_Aug91/AA-PD6PA-T…