The most interesting thing is that that post sat for months without the answer "why" it was done, but chatgpt knew, from the comment added 2h ago.
The j was to prevent forgery, or altering the document. ii could be altered later to iii.. but if it was ij its obvious its been tampered with if it later appears as iji
The question was asked over 10 years ago and now it's getting clicks from HN someone's copypasted a claim from a LLM, possibly without verifying it. That is kind of interesting, but not in a good way.
The question was "asked Oct 10, 2013 at 1:54" and the answer (which explains why it was done) was "answered Oct 10, 2013 at 2:58". A more likely take on chatgpt's answer is that their anti-fraud explanation is not even correct; the 2013 answer provides citations from the time explaining why, and anti-fraud is not mentioned.
The j was to prevent forgery, or altering the document. ii could be altered later to iii.. but if it was ij its obvious its been tampered with if it later appears as iji