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I have similar experience to the OP, with programming a Filetab spinoff called Rapidgen several decades ago and have been periodically so nostalgic for the simplicity and elegance of detabs that I gone Googling for modern implementations.
Nice to see there is still some interest in the topic.
Back in the old days the number of columns was limited by the number of bits in an integer, I think, but with 64 bit integers available now that restriction should be somewhat more relaxed.