Thanks for looking Lena.
For now, I gave up (as often the case with JSONata) and went back to a familiar function node. A lot quicker to deal with! But I have to set myself (and others 
) a challenge from time-to-time.
Anyway, the output from today's and yesterday's efforts has been to produce a new devices structure. This combines my manual IP/Mac table with nmap discovery. I've started to build a uibuilder editable table so that I will be able to update things like descriptions and locations for devices.
I blame Paul @zenofmud for this distraction because I looked again at his excellent "ET Display Home" and decided that I wanted a version that didn't take up 300 tabs and that would use uibuilder instead of Dashboard
That then reminded me that I'd promised myself that I'd re-engineer my home automation reference data which in turn reminded me that I really needed a UI to administer all this stuff rather than manually editing it in the Editor.
Oh dear, what was that about addiction?!
