Right now we have a fairly extensive list of macros in the docinfo.
Many date back to Greg's original tex source, where they were abbreviated macros for author convenience.
That makes a lot of sense for the LaTeX --> PDF route, since no reader will ever see your macros.
But in HTML, someone using assistive features of MathJax is going to encounter those macros.
One that jumped out recently was using `\dx` as a shortcut for `\Delta x`.
I suspect one is unlikely to parse \dx as intended.
(Also, use of this shortcut doesn't begin until around Chapter 7. In Chapter 5, \Delta x is used.)
Is it worth doing an audit of these macros? Alex can correct me on this, but it seems to me that it would be better to either:
a) replace some of these shortcut macros with the LaTeX source
or
b) replace these macros with something more semantic.
In the latter case one might then be tempted to find those places where the macro wasn't used, and introduce the semantic macro.
This can be done by find-and-replace, so we don't have to worry about these being efficient to type.