2.1.6 Attributes Shared by all MathML Elements
https://www.w3.org/TR/mathml4/#fund_globatt

In addition to the attributes described specifically for each element, the attributes in the following table are allowed on every MathML element. Also allowed are attributes from the xml namespace, such as xml:lang, and attributes from namespaces other than MathML, which are ignored by default.

The addition of the intent attribute on MathML element introduces the notion of concept dictionaries and literal text that is meant to read by assistive technology. Because concept dictionaries and literal text contain human language, the specification should explain the role of the xml:lang attribute in determining how the concept dictionaries and literal text are read.