Thanks mesverrum
That's very useful to know, I'm making good progress
What confuses me now is why SolarWinds says "Some of the properties that can be used for Filtering Nodes are:"
Do you know where the others are specified (website / manual)?
I've tried to create a Custom HTML containing all the suggested properties with the syntax ${propertyName} (e.g. ${NodeID}, ${GroupStatus} [got an icon here], etc.), and it worked although not everything gets populated. Thank you.
I'll do some more tests to see what I get.