2012-11-25 ago Isabelle-specific implementation of quasi-abstract markup elements -- back to module arrangement before d83797ef0d2d;
2012-10-03 ago allow position constraints to coexist with 0 or 1 sort constraints;
2012-10-01 ago report sort assignment of visible type variables;
2011-11-28 ago separate module for concrete Isabelle markup;
2011-11-10 ago more efficient prepare_sorts -- bypass encoded positions;
2011-11-10 ago pass term positions into check phase, where resulting types are reported accordingly, and eventually shown as tooltips;
2011-04-06 ago separate structure Term_Position;