Dear Doktor,
the file kded_device_automounterrc contains:
[Devices][/org/freedesktop/UDisks2/block_devices/sda11]
EverMounted=true
Icon=drive-harddisk
LastNameSeen=23,4 GiB harde schijf
LastSeenMounted=false
This was the case when I was asked for the root password tot mount this partition every time I logged in. I replaced this file with one from another M6 installation. After this I was no longer asked, but the stanza about sda11 was exactly the same. This is why I asked if there is another file somewhere that I died not yet find.
This partition is not mentioned in fstab, because normally I won't need it for my M6 installation on this computer. Sda11 is mentioned in Dolphin in the Places panel with the other partitions. When I want to mount it, I am asked for the root password, as expected. None of the other partitions tried to be mounted at login.
I think it very strange that the asking for the root password for sda11 at login ceased after the replacing of the file kded_device_automounterrc with one that was exactly the same as the foregoing. This is why I asked for further explanation.
Thank you and greetings,
Erik.