Thirty-seven years of unbroken revision history
The Xi-Text spooler's first recorded revision is dated 27 September 1989. The history runs from there to this month's release without a gap.
The oldest entry in the Xi-Text source history carries a note from whoever wrote it:
This is version 11 of the Spooler. It is now held under RCS not SCCS
It is dated 27 September 1989. The Xi-Batch scheduler's initial revision follows a year later, on 26 September 1990. Both histories run from there to the release made this month, unbroken - 103 commits in Xi-Batch during 2026 alone.
Why it is worth saying
Software that runs an overnight batch is bought on the expectation that it will still be there in ten years. That is an easy thing to assert and a hard thing to evidence, and most suppliers can only point at their current roadmap.
Thirty-seven years of continuous revision history is a different kind of evidence. It means every line in the product can be traced to the change that introduced it and the reason it was made, that nothing has been rewritten from scratch and quietly lost its history, and that the people maintaining it today are working on the same artefact rather than a reconstruction of it.
It is also why a fault reported against a release from 2014 can still be answered. The code that produced it is still there to read.