Thanks for the reply ... it serves to reinforce that I've not been entirely stupid so far, because I've tried that, and it achieves half of what I want. The problem is that I want links in the nodes - that's why I'm asking for HTML specifically.

I know I'm at risk here of asking for Y when actually I want to achieve Z and the best way is to use X, but seriously, if the nodes are HTML then I can do things in them already, but if they are SVG then I need to re-learn all the capabilities in a new language, and not leverage what I already know.

I want to have boxes with arrows between them. I want them laid out semi-automatically in a hierarchical fashion. The boxes should contain HTML, so I can put text and links in them.

However ...

It's looking like I need to generate SVG. I can generate plain SVG using DOT/GraphViz, but then I can't put links in the nodes. So I need to parse and post-process the SVG to insert the links, and it all just seems too hard.

I'm not saying it should be easy, but it should be easier than this. Someone must have done something similar, there must be a library. The art must have progressed beyond he graphical equivalent of machine code, but it seems not even to have got as far as assembly language.

I can't believe people assemble these sorts of displays by hand ...

Am I asking the wrong question?