minor improvements to typesetting source2e;

get rid of some overfull boxes (more to do);
suppress spurious l3doc warnings about using internals;

base/fontdef.dtx

@@ -39,7 +39,7 @@
 %<driver, >\ProvidesFile{fontdef.drv}
 % \fi
 %          \ProvidesFile{fontdef.dtx}
-%<-latexrelease>           [2020/11/24 v3.0i LaTeX Kernel
+%<-latexrelease>           [2021/01/15 v3.0i LaTeX Kernel
 % \iftrue  (\else
 %<text,   >(Text
 %<math,   >(Math
@@ -227,7 +227,7 @@
 %    described in \texttt{ltoutenc.dtx}.
 %
 %    By convention, text  encoding specific declarations, including the
-%    declaration |\DeclareFontEncoding|, are kept in separate file of
+%    |\DeclareFontEncoding| declaration, are kept in separate file of
 %    the form \meta{enc}\texttt{enc.def}, e.g.~\texttt{ot1enc.def}. This
 %    allows other applications to make use of the declarations as
 %    well.

base/ltclass.dtx

@@ -33,7 +33,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltclass.dtx}
-             [2020/12/17 v1.3v LaTeX Kernel (Class & Package Interface)]
+             [2021/01/15 v1.3v LaTeX Kernel (Class & Package Interface)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltclass.dtx}
@@ -2640,7 +2640,8 @@
 % Text before the |\end|, write it with a warning.
 %    \begin{macrocode}
           \@latex@warning{Writing text `##1' before %
-             \string\end{\@currenvir}\MessageBreak as last line of \@curr@file}%
+            \string\end{\@currenvir}\MessageBreak
+            as last line of \@curr@file}%
         \immediate\write\reserved@c{##1}%
       \fi%
       \ifx\relax##2\relax%
@@ -2675,7 +2676,8 @@
 %</2ekernel|latexrelease>
 %<latexrelease>\EndIncludeInRelease
 %<latexrelease>\IncludeInRelease{2019/10/01}%
-%<latexrelease>                 {\filec@ntents}{Spaces in file names + optional arg}%
+%<latexrelease>    {\filec@ntents}{Spaces in file names + optional arg}%
+%<latexrelease>
 %<latexrelease>\def\filecontents{\@tempswatrue\@fileswtrue
 %<latexrelease>  \@ifnextchar[\filec@ntents@opt\filec@ntents
 %<latexrelease>}
@@ -2805,7 +2807,7 @@
 %<latexrelease>\endgroup%
 %<latexrelease>\EndIncludeInRelease
 %<latexrelease>\IncludeInRelease{0000/00/00}%
-%<latexrelease>                 {\filec@ntents}{Spaces in file names + optional arg}%
+%<latexrelease>    {\filec@ntents}{Spaces in file names + optional arg}%
 %<latexrelease>
 %<latexrelease>\let\filec@ntents@opt        \@undefined
 %<latexrelease>\let\filec@ntents@force      \@undefined

base/ltdefns.dtx

@@ -32,7 +32,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltdefns.dtx}
-             [2020/11/25 v1.5o LaTeX Kernel (definition commands)]
+             [2021/01/15 v1.5o LaTeX Kernel (definition commands)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltdefns.dtx}
@@ -1471,7 +1471,7 @@
 %     \ldots
 %   \end{quote}
 %   \cs{robust@command@act} will iterate over the \meta{action-list}, evaluating
-%   each \meta{if-type-$n$}\meta{robust-cmd}|{|\meta{true}|}{|\meta{false}|}|.
+%   each \meta{if-type-$n$} \meta{robust-cmd} |{|\meta{true}|}{|\meta{false}|}|.
 %   If the \meta{if-type-$n$} conditional returns \meta{true}, then
 %   \meta{act-type-$n$}\meta{act-arg} is executed, and the loop ends.  If the
 %   conditional returns \meta{false}, then \meta{if-type-$n+1$} is executed in

base/ltdirchk.dtx

@@ -37,7 +37,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltdirchk.dtx}
-             [2020/12/05 v1.3a LaTeX Kernel (System Dependent Parts)]
+             [2021/01/15 v1.3a LaTeX Kernel (System Dependent Parts)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltdirchk.dtx}
@@ -127,14 +127,16 @@
 % |\input@path| should expand to a list of such directories, each in a
 % |{}| group.
 %
+% \begin{sloppypar}
 % \DescribeMacro{\filename@parse}
 % After a call of the form: |\filename@parse{|\meta{filename}|}|, the
-% three macros |\filename@area|,|\filename@base|,|\filename@ext| should
+% three macros |\filename@area|, |\filename@base| and |\filename@ext| should
 % be defined to be the `area' (or directory), basename and
 % extension respectively. If there was no extension specified in
 % \meta{filename}, |\filename@ext| should be |\let| to |\relax| (so this
 % case may be tested with |\@ifundefined{filename@ext}| and, perhaps a
 % default extension substituted).
+% \end{sloppypar}
 %
 % Normally one would not need to define this macro in |texsys.cfg| as
 % the automatic tests can supply parsers that work with UNIX and VMS and
@@ -470,14 +472,16 @@
 % |{}| group.
 %
 %
+% \begin{sloppypar}
 % \DescribeMacro{\filename@parse}
 % After a call of the form: |\filename@parse{|\meta{filename}|}|, the
-% three macros |\filename@area|,|\filename@base|,|\filename@ext| should
+% three macros |\filename@area|, |\filename@base|, |\filename@ext| should
 % be defined to be the `area' (or directory), basename and
 % extension respectively. If there was no extension specified in
 % \meta{filename}, |\filename@ext| should be |\let| to |\relax| (so this
 % case may be tested with |\@ifundefined{filename@ext}| and, perhaps a
 % default extension substituted).
+% \end{sloppypar}
 %
 % Normally one would not need to define this macro in |texsys.cfg| as
 % the automatic tests can supply parsers that work with UNIX and VMS

base/ltexpl.dtx

@@ -33,7 +33,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltexpl.dtx}
-             [2020/12/18 v1.2h LaTeX Kernel (expl3-dependent code)]
+             [2021/01/15 v1.2h LaTeX Kernel (expl3-dependent code)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltexpl.dtx}
@@ -188,7 +188,9 @@
 % In \texttt{2ekernel} mode, an error is fatal and building the format
 % is aborted. Use \verb=\batchmode \read -1 to \tokenlist=, which errors
 % with
-% \verb=! Emergency stop. (cannot \read from terminal in nonstop modes)=
+%\begin{verbatim}        
+%   ! Emergency stop. (cannot \read from terminal in nonstop modes)
+%\end{verbatim}        
 % and aborts the \TeX{} run.  In \texttt{latexrelease} mode, raise an
 % error and do nothing.  Both ways, the error message shows the minimum
 % \textsf{expl3} engine requirements.

base/ltfilehook.dtx

@@ -622,6 +622,7 @@
 %    When rolling forward the following expl3 functions may not be defined.
 %    If we roll back the code does nothing.
 % \changes{v1.0d}{2020/11/24}{Support for roll forward (gh/434)}
+% \InternalDetectionOff
 %    \begin{macrocode}
 %<latexrelease>\IncludeInRelease{2020/10/01}%
 %<latexrelease>                 {\file_parse_full_name_apply:nN}{Roll forward help}%
@@ -643,7 +644,8 @@
 %<latexrelease>  {
 %<latexrelease>    \tl_if_empty:nTF {#3}
 %<latexrelease>      { \__file_parse_full_name_base:nw { } #2 . \s__file_stop {#1} }
-%<latexrelease>      { \__file_parse_full_name_area:nw { #1 / #2 } #3 \s__file_stop }
+%<latexrelease>      { \__file_parse_full_name_area:nw { #1 / #2 }
+%<latexrelease>                                        #3 \s__file_stop }
 %<latexrelease>  }
 %<latexrelease>\cs_new:Npn \__file_parse_full_name_base:nw #1 #2 . #3 \s__file_stop
 %<latexrelease>  {
@@ -657,7 +659,8 @@
 %<latexrelease>          }
 %<latexrelease>          { \__file_parse_full_name_tidy:nnnN {#1} { .#2 } }
 %<latexrelease>      }
-%<latexrelease>      { \__file_parse_full_name_base:nw { #1 . #2 } #3 \s__file_stop }
+%<latexrelease>      { \__file_parse_full_name_base:nw { #1 . #2 }
+%<latexrelease>                                        #3 \s__file_stop }
 %<latexrelease>  }
 %<latexrelease>\cs_new:Npn \__file_parse_full_name_tidy:nnnN #1 #2 #3 #4
 %<latexrelease>  {
@@ -675,6 +678,7 @@
 %<latexrelease>\EndIncludeInRelease
 %<*2ekernel>
 %    \end{macrocode}
+% \InternalDetectionOn
 %
 %    \begin{macrocode}
 %<@@=>
@@ -897,7 +901,8 @@
           @file-subst@
           \@@_subst_file_normalize:Nn \use_ii_iii:nnn {#1}
         }
-        { \@@_subst_file_normalize:Nn \@@_file_name_compose:nnn {#2} }
+        { \@@_subst_file_normalize:Nn \@@_file_name_compose:nnn
+                                      {#2} }
     \group_end:
   }
 \cs_new_protected:Npn \@@_subst_remove:n #1
@@ -1106,7 +1111,8 @@
   \expandafter\ifx\csname\endcsname#1%
     .tex\else\string#1\fi}
 %    \end{macrocode}
-%    
+%
+%   \begin{sloppypar}
 %   Then we call \cs{@expl@@@filehook@set@curr@file@@nNN} once for
 %   \cs{@curr@file} to set \cs[no-index]{CurrentFile(Path)Used} and once for
 %   \cs{@curr@file@reqd} to set \cs[no-index]{CurrentFile(Path)}.
@@ -1116,6 +1122,7 @@
 %   \cs{@curr@file} and \cs{@curr@file@reqd} differ.  This macro is
 %   issued separate from \cs{set@curr@file} because it changes
 %   \cs{CurrentFile}, and side-effects would quickly get out of control.
+%   \end{sloppypar}
 %    \begin{macrocode}
 \def\@filehook@set@CurrentFile{%
   \@expl@@@filehook@set@curr@file@@nNN{\@curr@file}%
@@ -1185,7 +1192,7 @@
 %</2ekernel>
 %<*2ekernel|latexrelease>
 %<latexrelease>\IncludeInRelease{2020/10/01}%
-%<latexrelease>          {\@@_resolve_file_subst:w}{Replace files detect loops}%
+%<latexrelease>     {\@@_resolve_file_subst:w}{Replace files detect loops}%
 \ExplSyntaxOn
 \cs_new:Npn \@@_resolve_file_subst:w #1 \@nil
   { \@@_file_parse_full_name:nN {#1} \@@_file_subst_begin:nnn }
@@ -1284,7 +1291,7 @@
 %</2ekernel>
 %<*2ekernel|latexrelease>
 %<latexrelease>\IncludeInRelease{2020/10/01}%
-%<latexrelease>         {\@@_file_subst_tortoise_hare:nn}{Tortoise and Hare}%
+%<latexrelease>  {\@@_file_subst_tortoise_hare:nn}{Tortoise and Hare}%
 \ExplSyntaxOn
 \cs_new:Npn \@@_file_subst_tortoise_hare:nn #1 #2 #3
   {
@@ -1437,7 +1444,7 @@
 %    \begin{macrocode}
 %<@@=>
 %    \end{macrocode}
-% 
+%  \InternalDetectionOff
 %    \begin{macrocode}
 %</2ekernel>
 %<*2ekernel|latexrelease>
@@ -1495,6 +1502,7 @@
 \cs_new_eq:NN \@expl@@@filehook@file@pop@assign@@nnnn
               \__filehook_file_pop_assign:nnnn
 %    \end{macrocode}
+%  \InternalDetectionOn
 %    
 %
 %    \begin{macrocode}

base/ltfiles.dtx

@@ -32,7 +32,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltfiles.dtx}
-             [2020/12/04 v1.2j LaTeX Kernel (File Handling)]
+             [2021/01/15 v1.2j LaTeX Kernel (File Handling)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltfiles.dtx}
@@ -458,12 +458,14 @@
 %    applied several times with harmful effects. We therefore
 %    explicitly drop it at this point. the coding is somewhat obscure
 %    due to the name of the macro which requires constructing.
+% \InternalDetectionOff
 %    \begin{macrocode}
 \edef \@kernel@after@begindocument@before {%
   \let\expandafter\noexpand\csname
        __hook env/document/begin\endcsname
   \noexpand\@empty}
 %    \end{macrocode}
+% \InternalDetectionOn
 %
 %    \begin{macrocode}
 \let \@kernel@before@begindocument \@empty
@@ -996,10 +998,11 @@
 %   A side effect of the new code is that we will see quotes around
 %   file name displays where there haven't been any before.
 %
-%   For compatibility with existing code using |{abc}.tex| or |{one.two}.png|
-%   an initial brace group is discarded before expansion and |\string| is applied
-%   The content of the brace group is discarded. This means that a leading space
-%   will be lost unless protected (by |{ }| or |" "| or |\space|) but filenames
+%   For compatibility with existing code using |{abc}.tex| or
+%   |{one.two}.png|, an initial brace group is discarded before
+%   expansion and |\string| is applied.  The content of the brace
+%   group is discarded. This means that a leading space will be lost
+%   unless protected (by |{ }| or |" "| or |\space|) but filenames
 %   with a space are hopefully rare.
 %
 %  \changes{v1.2a}{2019/07/01}{Support UTF-8}

base/ltfinal.dtx

@@ -33,7 +33,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltfinal.dtx}
-             [2021/01/06 v2.2l LaTeX Kernel (Final Settings)]
+             [2021/01/15 v2.2l LaTeX Kernel (Final Settings)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltfinal.dtx}
@@ -525,12 +525,13 @@
 %</2ekernel>
 %<*2ekernel|latexrelease>
 %<latexrelease>\IncludeInRelease{2017/04/15}%
-%<latexrelease>                 {\document@default@language}{Save language for hyphenation}%
+%<latexrelease>       {\document@default@language}{Save language for hyphenation}%
 \let\document@default@language\m@ne
 %</2ekernel|latexrelease>
 %<latexrelease>\EndIncludeInRelease
 %<latexrelease>\IncludeInRelease{0000/00/00}%
-%<latexrelease>                 {\document@default@language}{Save language for hyphenation}%
+%<latexrelease>       {\document@default@language}{Save language for hyphenation}%
+%
 %<latexrelease>\let\document@default@language\@undefined
 %<latexrelease>\EndIncludeInRelease
 %<*2ekernel>

base/ltfssaxes.dtx

@@ -35,7 +35,7 @@
 %
 %
 \ProvidesFile{ltfssaxes.dtx}
-             [2020/12/22 v1.0h LaTeX Kernel (NFSS Axes handing)]
+             [2021/01/15 v1.0h LaTeX Kernel (NFSS Axes handing)]
 % \iffalse
 \documentclass{ltxdoc}
 \begin{document}
@@ -764,8 +764,10 @@
 %<latexrelease>\IncludeInRelease{2020/02/02}%
 %<latexrelease>                 {\fontseries}{delay fontseries update}%
 %<latexrelease>
-%<latexrelease>\DeclareRobustCommand\fontseries[1]{\@forced@seriesfalse\merge@font@series{#1}}
-%<latexrelease>\DeclareRobustCommand\fontseriesforce[1]{\@forced@seriestrue\edef\f@series{#1}}
+%<latexrelease>\DeclareRobustCommand\fontseries[1]{\@forced@seriesfalse
+%<latexrelease>                                    \merge@font@series{#1}}
+%<latexrelease>\DeclareRobustCommand\fontseriesforce[1]{\@forced@seriestrue
+%<latexrelease>                                         \edef\f@series{#1}}
 %<latexrelease>\let\delayed@f@adjustment\@undefined
 %<latexrelease>
 %    \end{macrocode}

base/ltfssdcl.dtx

@@ -36,7 +36,7 @@
 %
 %
 \ProvidesFile{ltfssdcl.dtx}
-            [2020/12/05 v3.0v LaTeX Kernel (NFSS Declarative Interface)]
+            [2021/01/15 v3.0v LaTeX Kernel (NFSS Declarative Interface)]
 % \iffalse
 \documentclass{ltxdoc}
 \begin{document}
@@ -1526,7 +1526,7 @@
 \def\set@mathdelimiter#1#2#3#4#5#6{%
 %    \end{macrocode}
 %    We use \cs{protected} not \cs{MakeRobust} so that
-%    \verb=\bigl\lfoor= etc.\ works inside \cs{protected@edef}.
+%    \verb=\bigl\lfoor= etc.\ works inside the argument of \cs{protected@edef}.
 % \changes{v3.0s}{2019/08/27}{Make math delimiters robust}
 % \changes{v3.0t}{2020/01/20}{fix for gh/251}
 %    \begin{macrocode}
@@ -1733,7 +1733,7 @@
       \relax
 %    \end{macrocode}
 %    If it is undefined, fine otherwise check if it is a math alphabet
-%    defined via |\DeclareSymbolFontAlphabet|:
+%    defined via \\ |\DeclareSymbolFontAlphabet|:
 %    \begin{macrocode}
       \else
         \edef\reserved@a{%