I write on a variety of topics, only some of which it's appropriate to have mathematical typesetting for. To avoid triggering a math rendering engine on unrelated use of $purious dollar sign$, while activating it when $\text{necessary}\wedge\text{appropriate}$, I decided to restrict them to only <… lang="x-mathjax">. Here's how that's done (for v3): MathJax = { tex: { inlineMath: [ ['$', '$'] ] }, startup: { elements: [':lang("x-mathjax")'] } }; …