fmtmathjax.spad line 83 [edit on github]
FormatMathJax provides a coercion from OutputForm to a LaTeX format in a variant that can be understood by MahtJax (https://www.mathjax.org).
environmnt(env, x, sep) returns a handler that typesets its arguments (without parentheses) in a LaTeX environment with name env. The string x is put right after the start of the environment. The arguments are separated by the string sep.