Recently the msixpackaging project was updated to include updated schema changes (THANK YOU)! While affecting nearly all of the existing schemas for the purpose of integrating in new parts, in includes what seems to be 2+ years of new schemas unseen until now.
I believe that the following schemas are not covered in the existing documentation for MSIX schemas and need to be added to the online documentation:
Uap11 - Uap13
Preview MsixAppCompat 1 & 3 (although there may also be a v2 we haven't seen???)
As an added note about the online documentation, it would be much more helpful to partners and customers if the scope of the documentation expanded slightly. Often the pages list only the rudimentary information about an element and its attributes. While I have detected improvements in where elements fit in, it still generally lacks:
a useful description of why someone would use the element,
what effect it actually has in the deployed package,
and restrictions/limitations such as certain OS minimum versions.