In knee-jerk reaction to something that appeared on comp.compilers, I figured I'd go off and write a TeX file that defined, and invoked, a macro named \{} (that is, the name of the macro is \{}, not empty).

( Read more... )

This has all kinds of terrible implications. Mostly they're only exploited by the LaTeX \makeatletter and \makeatother macros to "hide" things from non-package code. But nothing actually stops you from creating a macro named \$; if I understand the implications of \active, nothing stops you from creating a macro named just $ either and thereby confusing everybody who expects math mode.