OK, I think I found the problem. I did it by copying subsections of my design to a new schematic, then running gnetlist until the "U?" was found, then deleted objects until I no longer got the "U?" nonsense. It was a screwed-up IC symbol; apparently it put gnetlist into a tizzy. I guess gnetlist reads all the schematic files before it starts working on the net, so it can't give me a "Bad !@#$%^ at or near line #123" sort of message. Oh, well. Thanks for the help, Marshall
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