diff --git a/doc/datamash.texi b/doc/datamash.texi
index 843362c..806daf3 100644
--- a/doc/datamash.texi
+++ b/doc/datamash.texi
@@ -9,6 +9,7 @@
 @c Combine everything into one index (arbitrarily chosen to be the
 @c concept index).
 @syncodeindex op cp
+@syncodeindex vr cp
 @c %**end of header
 
 @copying
@@ -157,6 +158,10 @@ on the input data. If @option{--group} is used, each operation is performed
 on every group. If @option{--group} is not used, each operation is performed on
 all the values in the input file.
 
+@vindex LC_NUMERIC
+The @env{LC_NUMERIC} locale specifies the decimal-point character and the
+thousands separator.
+
 @exdent @command{datamash} supports the following operations:
 
 @table @asis