[Koha] Setting up an SRU target

[Rubeno]

Hello all,

I'm trying to set up an SRU target and can't seem to find the way.

The SRU server is the Austrian National Library. Here's the info for 
their SRU server:

    https://obv-at-oenb.alma.exlibrisgroup.com/view/sru/43ACC_ONB?version=1.2&operation=explain

They provide some more info here:

    https://labs.onb.ac.at/en/datasets/catalogue/

So I'm trying to look for a book that I know exists, because I can 
retrieve it in XML like this:

    https://obv-at-oenb.alma.exlibrisgroup.com/view/sru/43ACC_ONB?version=1.2&query=alma.title=terminaro%20and%20alma.creator=Portmann&operation=searchRetrieve

However I don't know what to set up in the 'Additional SRU options' 
field. I've tried several combinations of 
"sru=get,sru_version=1.2,operation=searchRetrieve", but I never get any hit.

As for the SRU field mapping, I'm trying this: 
title=title,isbn=isbn,author=creator,issn=issn,subject=subjects

The manual https://software.indexdata.com/yaz/doc/zoom.html that is 
linked to in the Koha interface is complete gibberish to me.

I have no installation of my own yet (still deciding whether Koha is 
manageable for my association), so I'm using this demo server:

    https://intra1.orex.es/

Can anybody help, at least describing a working setup for other SRU 
targets? Thanks!

Rubeno