1999-01-12 ago eliminated global/local names;
1999-01-07 ago ZF: the natural numbers as a datatype
1998-12-28 ago new inductive, datatype and primrec packages, etc.
1997-10-17 ago (co) inductive / datatype package adapted to qualified names;
1997-08-06 ago use ThySyn.add_syntax;
1997-08-06 ago Replaced "init_thy_reader" by "set_parser".
1997-06-05 ago A slight simplification of optstring
1996-01-30 ago expanded tabs
1995-12-28 ago Reduced indentation; no change in function
1995-12-22 ago Improving space efficiency of inductive/datatype definitions.
1994-12-16 ago Defines ZF theory sections (inductive, datatype) at the start/