If there is XML, there should also be WML (for Wayland).

Oh no, WML was for wireless. But it's obsolete, so free for reuse.

https://en.wikipedia.org/wiki/Wireless_Markup_Language

Wireless Markup Language - Wikipedia

@CyReVolt Those were the days. I remember writing a Twitter to WAP gateway (presenting WML), so I could check it on my Nokia dumbphone :)