Need to add user selection attributes

Some assistive technology (AT) programs use MathML or OMML as conduits for generating math speech and braille from math-enabled apps. In addition, they would like to use these formats for editing math text as well as speaking it and displaying it on refreshable braille displays. To this end, the formats need selection attributes that identify where the user selection is or should be within the MathML or OMML. These selection attributes are intended for accessibility purposes; MathML/OMML in copy, paste, and files ordinarily wouldn’t contain such attributes.

The post MathML and OMML User Selection Attributes describes this is some detail. The applet UnicodeMathML implements the selection attributes with slightly different names: "selanchor" and "selfocus", which correspond to the selection object in the browser DOM. If the selection is degenerate, i.e., an insertion point, only the selanchor attribute is written.

Start by reading the linked “MathML and OMML User Selection Attributes” post and comparing the UnicodeMathML playground’s selanchor and selfocus behavior. Determine how the MathML specification should define selection attributes for assistive-technology editing and insertion points; done means the required attribute semantics and naming are specified consistently.