https://tech.ebu.ch/docs/tech/tech3285s5.pdf
The axml chunk may contain any data compliant with the XML 1.0 format or later, a widespread
format for data exchange [4]. Note that the chunk may contain XML fragments from more than one Schema.
The axml chunk may occur in any order with the other BWF chunks within the same file.
https://tech.ebu.ch/docs/tech/tech3285s5.pdf