[texhax] Forcing size changes in exponents

[Karl Berry]

    if you have the latest version of tex live
    (tex live 2015), \rm and the other 2-letter
    font changes (except, i think, \em) have
    been disabled.

I don't see that (with a sigh of relief).

\documentclass{article}
\begin{document}
$A^{\rm op}$

$A^{A^{\rm op}}$
\end{document}

works for me in current TL.  No errors, anyway.  Looks to me that the
font size decreased as expected, too.

Actually disabling \rm et al. would be such a major break in
compatibility that I sincerely hope, and expect, it will never happen.

k