lu6etj wrote in
:

....
is very strict with wording and precision of terms :) then I thought
it was no exaggeration from me ask whether it is correct use the term
"balun" when both sides are "un", hi hi.

Perhaps the term 'common mode choke' works?

I did see a raging argument someone online (eham?) just recently where
parties were arguing that a 4:1 Guanella current balun could be wound on
a single toroid, it was the way Guanella intended it they said, but they
argued that use of two ferrite sticks for such a device was wrong.

In fact, Guanella's article describes his 1:1 balun without any magnetic
core material, and the 4:1 balun as a connected pair of 1:1 baluns with
no (ie negligible) magnetic coupling. Yet I have seen commercial sites
selling a Guanella 4:1 current balun on a single core, arguing that
Sevick said it was ok in a certain context... a context that is unlikely
to ever exist in an antenna system. But hey, Sevick is Mr Baluns, so they
sell. That context relates to another dimension of the balanced /
symmetric issue.

Back to the Carolina Windom, a common explanation holds that there is
common mode current on the feedline between the dipole feedpoint and the
'isolator'. The notion that common mode current exists on one side of the
isolator and not on the other is an interesting one, one better explained
by advertising hyperbole than radiocommunications theory.

Owen