Feature T401 is not listed in the SQL standard. Must have been a mistake.

src/backend/catalog/sql_features.txt

@@ -454,7 +454,6 @@ T326	Table functions			NO
 T331	Basic roles			NO	
 T332	Extended roles			NO	
 T351	Bracketed SQL comments (/*...*/ comments)			YES	
-T401	INSERT into a cursor			NO	
 T431	Extended grouping capabilities			NO	
 T432	Nested and concatenated GROUPING SETS			NO	
 T433	Multiargument GROUPING function			NO