% Minimized from latex3/latex2e `required/tools/theorem.dtx` (smoke-test issue
% #71). The documentation layer writes the same split environment definition the
% code layer does: `\begin` in one `\def` body, `\end` in another. Both halves
% sit inside a brace group the *doc line itself* opened, so the group-boundary
% gate applies here exactly as it does in code -- the `.dtx` doc-margin exemption
% is only for braces the code layer stranded.
%
% \def\deflabel#1{\ttfamily #1\hfill}
% \def\deflist#1{\begin{list}{}{\settowidth\labelwidth{\ttfamily #1}%
% \setlength\leftmargin\labelwidth
% \let\makelabel\deflabel}}
% \def\enddeflist{\end{list}}
%
% A doc-layer environment that is *not* inside a doc-line group still pairs
% across the intervening `macrocode` chunk, exemption intact.
%
% \begin{macro}{\thing}
% \begin{macrocode}
\def\thing{ok}
% \end{macrocode}
% \end{macro}