src/Pure/Isar/keyword.ML
2010-11-06 ago added Keyword.is_heading (cf. Scala version);
2010-08-14 ago Keyword.status: always suppress position;
2010-08-08 ago explicitly distinguish Output.status (essential feedback) vs. Output.report (useful markup);
2010-05-17 ago centralized legacy aliases;
2010-05-15 ago renamed structure OuterKeyword to Keyword and OuterParse to Parse, keeping the old names as legacy aliases for some time;