CTAN sync 202108280300

1 files changed, 9 insertions, 0 deletions

diff --git a/macros/latex/contrib/l3kernel/source3body.tex b/macros/latex/contrib/l3kernel/source3body.tex
index 946f7a4abc..a2e87856bd 100644
--- a/macros/latex/contrib/l3kernel/source3body.tex
+++ b/macros/latex/contrib/l3kernel/source3body.tex
@@ -328,6 +328,15 @@ following variable types:
   \item[\texttt{regex}] Regular expression.
 \end{description}
 
+\subsection{Scratch variables}
+
+Modules focussed on variable usage typically provide four scratch variables,
+two local and two global, with names of the form
+\cs{\meta{scope}_tmpa_\meta{type}}/\cs{\meta{scope}_tmpb_\meta{type}}. These
+are never used by the core code. The nature of \TeX{} grouping means that as
+with any other scratch variable, these should only be set and used with no
+intervening third-party code.
+
 \subsection{Terminological inexactitude}
 
 A word of warning. In this document, and others referring to the \pkg{expl3}