# Where are the MathJax LaTeX symbols/environments documented?

At the following link in the MathJax documentation it lists the supported LaTeX symbols alphabetically that it supports, followed by the set of supported environments...

http://www.mathjax.org/docs/2.0/tex.html#symbols

My question is where are each of these symbols/enviornments described and documented?

For example, where is the definitive description of the \above symbol ?

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Is the focus here MathJax or the more general syntax for math mode commands for (La)TeX? The latter is on-topic, but MathJax-specifics are off-topic as MathJax does not actually use TeX, only LaTeX-like math commands. –  Joseph Wright Mar 25 '12 at 9:13
The commands and their usage are explained in detail in this page that is linked to the page you mentioned. –  egreg Mar 25 '12 at 9:16
The advantage of just typing TeX equations in html that MathJax provides is so awesome that it never occurred to me that this might be off-topic. I assumed that the original question was aimed at extending MathJax support for LaTeX. I think egreg's answer was more appropriate. –  Scott Prahl Mar 25 '12 at 20:17
@JosephWright: Sorry Joseph I disagree. The LaTeX-like features of MathJax are most certainly a TeX-related tool, and as such are on topic at tex.stackexchange.com, as per point 4 of FAQ. –  Andrew Tomazos Mar 25 '12 at 20:40
@user1131467: No, it's not really a TeX-related tool, because it doesn't use Tex or is used together with it. It only uses a subset of the TeX syntax, plus maybe some extra things. A question about the description of LaTeX commands is on-topic, but MathJax documentation would be off-topic. Now you ask about a description for TeX commands (which is on-topic) but for a different software (off-topic), so your question is kind of in the gray area. –  Martin Scharrer Mar 26 '12 at 14:36

The Web page

http://www.onemathematicalcat.org/MathJaxDocumentation/TeXSyntax.htm

has a very detailed explanation of each LaTeX command that is interpreted by MathJax.

The commands are of course explained in the LaTeX manual or in many user's guide; the commands that are labeled "AMS" are described in the documentation of amsmath.

A particularly recommended guide about math in LaTeX is "Math mode" by Herbert Voß (although more focused on usage in LaTeX).

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The definitive answers are in the JavaScript source code. The best way to examine the source is to download the source from GitHub

git clone http://github.com/mathjax/MathJax


Once you have the source files, then it is possible to see exactly how \above is implemented and you'll find that \above is defined in unpacked/jax/input/TeX/jax.js as 'Over', which in turn is implemented using the following JavaScript

Over: function (name,open,close) {
var mml = STACKITEM.over().With({name: name});
if (open || close) {
mml.open = open; mml.close = close;
} else if (name.match(/withdelims\$/)) {
mml.open  = this.GetDelimiter(name);
mml.close = this.GetDelimiter(name);
}
if (name.match(/^\\above/)) {mml.thickness = this.GetDimen(name)}
else if (name.match(/^\\atop/) || open || close) {mml.thickness = 0}
this.Push(mml);
},


which is pretty inscrutable. Simpler TeX constructs like \alpha are simply mapped to the corresponding unicode value

alpha:        '03B1',

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