My team has been using ChatGPT for generating breakdowns of legacy code, including thousands of Fortran files for which there's no official documentation and the original developers are long retired. This is probably one of the best use cases I have seen so far of LLM aiding software development. With the overwhelming amount of legacy code running critical infrastructure in the US, I can see the enormous value LLMs can provide when tuned for documenting systems written in legacy languages like Fortran, Cobol and Delphi.