diff -r 9fe6c4633ed6 -r d2cd05c5e01a stage4/generate_c/generate_c_il.cc
--- a/stage4/generate_c/generate_c_il.cc	Fri Mar 09 10:52:23 2012 +0000
+++ b/stage4/generate_c/generate_c_il.cc	Fri Mar 09 17:58:19 2012 +0000
@@ -1640,6 +1640,12 @@
 }
 
 void *visit(NOT_operator_c *symbol)	{
+  /* NOTE: the standard allows syntax in which the NOT operator is followed by an optional <il_operand>
+   *              NOT [<il_operand>]
+   *       However, it does not define the semantic of the NOT operation when the <il_operand> is specified.
+   *       We therefore consider it an error if an il_operand is specified!
+   *       The error is caught in stage 3!
+   */  
   if ((NULL != this->current_operand) || (NULL != this->current_operand_type)) ERROR;
   XXX_operator(&(this->default_variable_name),
                search_expression_type->is_bool_type(this->default_variable_name.current_type)?" = !":" = ~",