--- a/doc/interpreter/basics.txi	Fri Jun 26 13:57:24 2020 -0700
+++ b/doc/interpreter/basics.txi	Sat Jun 27 12:01:33 2020 +0200
@@ -392,6 +392,22 @@
 invoke Octave with the @option{--verbose} option but without the
 @option{--silent} option.
 
+The startup files are always processes in the system's locale charset
+(independent of the .m file encoding that is set e.g. in the GUI properties).
+That is until a user manually sets the .m file encoding (e.g. in one of the
+startup files) and triggers re-parsing the .m files.  This can be done with the
+undocumented core function @code{__mfile_encoding__}:
+
+@example
+@group
+__mfile_encoding__ ("utf-8");  # set new encoding
+clear ("functions");  # re-parse all .m files in the new encoding
+@end group
+@end example
+
+This changes the encoding that is used to interpret all subsequently run startup
+and .m files (not including the currently executing file).
+
 @node Quitting Octave
 @section Quitting Octave
 @cindex exiting octave