2011-08-21 ago tuned delayed failure message;
2011-04-08 ago discontinued special treatment of structure Mixfix;
2010-11-28 ago Parse.liberal_name for document antiquotations and attributes;
2010-11-28 ago added Parse.literal_fact with proper inner_syntax markup (source position);
2010-05-17 ago centralized legacy aliases;
2010-05-15 ago renamed structure SpecParse to Parse_Spec, keeping the old name as alias for some time;