https://docs.digi.com/resources/documentation/digidocs/90001...

It's pretty simple actually.

> 'X weeks' or 'Y hours Z minutes'

PxW, PTyHzM. So simple that I learned it in a few seconds.

I learned it too. It's just ugly. Before I looked at the relevant section of the ISO 8601 duration format yesterday, I didn't know it. After I looked at it, I now know it, and I strongly dislike it.