The html-like system we have for formatting text in plotly.js is getting more and more complicated, and is used in more and more places. see plotly/plotly.js#1726 for the latest.

We should have a dedicated page to collect this, and somehow link it to the reference for each of the different attributes that can use it:

Our pseudo-html applies to really anywhere we display text: annotations, plot and axis titles, trace names. Also tick labels (categories, ticktext, tickprefix, ticksuffix...) and trace text and hovertext

cc @cldougl @etpinard