I did genuinely think it might have been about https://en.wikipedia.org/wiki/Molecular_descriptor (which, briefly, are like a 'kernel' in machine learning, or can be something like a Bloom Filter).
[1] https://stackoverflow.com/questions/36625892/descriptor-conc...
Adding a UI that presents the tags in the Algolia search might be the difficult-to-get-right part.
There was a lot of unusual things back then; now I think memory is flat so your stack address 1234 is the same as your code and data address 1234 (the exception being thread-local variables).