Subscripts do not seem to output MathML correctly

[johnhbenetech]

Description

When entering a subscript into mathlive or mathshare's implementation of mathlive (using something like 2_3 for instance) - the MathML generated in the sr-only span does not include the subscript.

Actual behavior

Resulting MathML only includes the main entry and omits the subscript

Expected Behavior

Resulting MathML should include msub element and content in the appropriate location

[timtsm]

Subscripts are reported in mathml if they are on letters. In addition to numbers, close parentheses and + signs, among others, don't report subscripts in mathml. Close parentheses, \imaginaryI, and \exponentialE (and + signs) also don't report superscripts, making (a+b)^2 the same as (a+b), i^2 the same as i, e^x just e (when i and e are the \imaginaryI and \exponentialE forms--regular letters i and e work), etc.

[timtsm]

Oh, and a_x^2 (or a^2_x) is reported in mathml as a^2 (a can be any other letter as far as I can see).