--- a/core/builtins/source.cif	Tue Oct 26 15:36:30 2010 +0100
+++ b/core/builtins/source.cif	Thu Oct 28 16:54:54 2010 +0100
@@ -40,9 +40,9 @@
 
 L<debug|debug>
 
-==argument filename script_file_name
+==argument filename script_file_name optional
 
-The name of the script file to be run.
+The name of the script file to be run. If not specified (or specified with zero length, i.e. ''), the script will be read from C<stdin>.
 
 ==argument string script_args optional last