MathML is a low-level specification for mathematical and scientific content on the Web and beyond.
Here is an example of Presentation MathML: and another:
|XML Entity Definitions||REC|
|Units in MathML||NOTE|
|Arabic mathematical notation||NOTE|
|Structured Types in MathML 2.0||NOTE|
|Bound Variables in MathML||NOTE|
|MathML Media-type Declarations||Note||Note|
|A MathML for CSS Profile||REC|
What is MathML teaches you how to create your first equation and to understand the base constructs of MathML.
Of course, nearly all software has bugs. And some programs are further ahead implementing MathML 3 than others.
You can also read and create issues on GitHub. (You need a (free) GitHub account to create a new issue.)
The ‘MathML Refresh’ Community Group developed drafts for MathML 4 and MathML Core, preparing for the Working Group. Anybody can join the group.
The Math Working Group is one of the oldest W3C Working Groups. During its first period of activity (1996–2004), it created and maintained versions 1 and 2 of MathML. During its second period (2006–2016), it created, among other things, MathML version 3 and saw it become an ISO standard.
Since April 2021, the group is developing a new revision of MathML, MathML version 4, as well as MathML Core, a subset that can be reliably displayed in web browsers.