% So, why are we not using \appdxsection here?
%
% Sit down, my child, and you shall hear a tale.  A tale of terrible
% danger and of great deeds by heroes who fought that danger but were
% ultimately defeated.  This is not a story with a happy ending.  Your
% father and I debated for a long time about whether you were old
% enough to hear it.  We eventually decided you were still too young,
% but you sneaked into my computer and are now reading it anyway, you
% little rascal!  Fine.  If you're old enough to break into the liquor
% cabinet, you're old enough to get drunk, as the saying goes.  (No
% one ever actually said this.  I just made it up.  But I'll bet that
% by this time next year it's trending on Twitter.)
% 
% Anyway, here's the deal:
%
% If we just use "\appdxsection{Foo}\label{appdx:foo}" here, then the
% first appendix's name will be something like "Appendix G".  In other
% words, the section numbering that we've been using so far will
% continue right on in to the appendix letters.  If the last
% non-appendix section was Section 6, then the first appendix will get
% named for the 7th letter of the alphabet.
%
% That sucks, but we all know what the solution is, right?  Just do:
%
%   \setcounter{section}{0}
%
%   (And actually, you can even combine that with another command,
%   "\renewcommand{\thesection}{\Alph{section}}", so that subsections
%   within the appendix get lovely appendix-y names like "A.1", "A.2",
%   "A.2.1", etc.)
%
% Ah, but there's a problem:
% 
% Now if you say "Section \ref{appdx:foo}" anywhere in the document,
% the ref's *link* will actually point to the page where -- you
% guessed it -- Section 1 is!  So while the reference's text would
% look correct (saying "Appendix A" or whatever), if you click on it
% it mysteriously jumps to Section 1, and if you hover over it, in
% Evince or in any other PDF reader that supports preview popups, you
% see a popup showing Section 1's header.
%
% I don't have a solution for this.  Or rather, I finally decided to
% stop shaving the LaTeX yak and just do it manually, with a regular
% unnumbered section that has "Appendix A:" in its title explicitly.
%
% Sometimes the dragon wins.