Ah ha!

I have solved the problem that prompted me to ask the above question.

The problem was that I had duplicate selection of the same map in my thconfig file.

A result of my idle double-clicking in the Map Structure pane in the XTherion compiler, and thinking I had removed the spurious entries so created.

For the TO DO list: Maybe it would be a good idea to test for duplicate map selection and report.  The errors that eventually occurred made me think there was an error in a scrap drawing.

Still, I’d like to know how to identify the objects referred to by the bracketed numbers, so I can tidy up the few “scrap outline intersects itself” errors that I get.

Bruce