should function exactly as \( \[ and \) and \] function in latex and do nothing in HTML mode or only do centering and line breaks in the case of display math
It doesn’t look like they were found to be useful and were largely ignored. If we preserve them they should probably
do the “right thing” for MathJax as well. It seems they weren’t updated when MathJax was introduced.
EV2 was a previous version of EV3 and is not used very much. It does have one significant feature which is worth
remembering. If I remember correctly EV3 first processes the contents of \{ \} (perl code), then interpolates variables
($var.) and finally processes the tex expressions inside \(\) and \[ \]. EV3 interpolates the variables first, then
evaluates perl code and finally the TeX expression. Often these two processes are equivalent but not always.
EV3 caused the fewest surprises so it is almost always used. Most problems using EV2 for legacy reasons
would work using EV3.
— Mike