First, I must extend thanks and gratitude to Megan of rapunzellstower.com and Kyle of fidgeting.net, whose seemingly-unrelated bug reports, two months apart, provided the solution to an ugly Quarto bug I had repeatedly glimpsed but been unable to personally reproduce.

Silly domesticat. (Most of my bug reports start like that.) Two months of off-and-on hunting for this bug, which consisted of seven characters in one file being misplaced. Which ones, you ask?

Oh, the closing FORM tag.