document which letter-like classes could do with the same fix

base/letter.dtx

@@ -1,6 +1,6 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 % The LaTeX3 Project and any individual authors listed elsewhere
 % in this file.
 %
@@ -45,7 +45,7 @@
 %<*driver>
        \ProvidesFile{letter.drv}
 %</driver>
-              [2020/12/27 v1.3c
+              [2021/01/07 v1.3c
 %<+letter>               Standard LaTeX document class]
 %    \end{macrocode}
 %
@@ -1025,6 +1025,20 @@
 %    was done simply at \verb=\\=. So we add \cs{expandafter} here so
 %    that is will be used and not typeset. A better fix would be to do
 %    a proper parsing but \ldots
+%
+%    Other classes based on \texttt{letter.cls} could benefit from the same fix, e.g.,
+%    \texttt{akletter.cls},
+%    \texttt{bletter.cls},
+%    \texttt{letter.cls},
+%    \texttt{chletter.cls},
+%    \texttt{extletter.cls},\\
+%    \texttt{frletter.cls},
+%    \texttt{hletter.cls},
+%    \texttt{scrlttr2.cls},
+%    \texttt{lettre.cls},
+%    \texttt{beletter.cls},\\
+%    \texttt{brief.cls} and perhaps others.
+%
 % \changes{v1.3c}{2020/12/28}{Add \cs{expandafter} (gh/427)}
 %    \begin{macrocode}
   {\raggedright \toname \expandafter\\\toaddress \par}%