Integrity, authenticity and RXSWIN, made practical.
RXSWIN is one of those acronyms that looks intimidating and turns out to be a simple, useful idea: a label that says exactly which approved software a vehicle type is running.
RXSWIN, the Regulation X Software Identification Number, links approved software versions to a vehicle type. It is central to UN R156, the regulation that governs software and over-the-air update management through a SUMS.
Why it exists
Type approval assumes the authority knows what it approved. But software changes constantly. RXSWIN is the mechanism that keeps approval and reality in sync: it identifies the certified software configuration, so everyone can tell whether a vehicle is running approved software and whether a given change affects the approval.
What it means for a software team
- Maintain a clear mapping between the software you build and the RXSWIN it belongs to.
- Know which changes are relevant to type approval, not every commit moves an RXSWIN, but security-relevant changes can.
- Tie RXSWIN handling into your SUMS and release process so it is updated deliberately, not forgotten.
Getting it right
Treat RXSWIN as part of your release engineering, not an afterthought at approval time. If your build and release pipeline already tracks versions cleanly, wiring RXSWIN in is mostly discipline.
To connect RXSWIN, your SUMS and OTA pipeline into one compliant picture, start with a gap assessment.