less markup: prefer "notatation" over "entity";

clarify comparison of output: ignore token positions, which are somewhat accidental;

clarified order of markup: more uniform input vs. output;

misc tuning;

clarified parse tree: always provide root node;

tuned signature;

tuned markup;

clarified markup: avoid conflict of "notation" with "entity", e.g. in "[x,y,z]" without spaces;

more flexible command syntax;

less markup (amending 07ad0b407d38): const = "" is mainly for parentheses syntax -- avoid entity_markup here;

more markup reports: notably "notation=..." within pretty blocks;

more parse tree positions;

more operations;

clarified order for 'print_syntax' command;

more accurate parse tree: retain all tokens (and thus positions);

more thorough markup reports (amending 0c6a600c8939 and 7f9e8516ca05): descend into vacuous nodes;

clarified comparison: prefer authentic nonterminal context, instead of somewhat accidental "const";

more detailed parse tree: retain nonterminal context as well;

clarified persistent data;

clarified input and output: support markup blocks via Bg/En; clarified datatype tree vs. tree_ops: reconstruct nested markup blocks via make_tree; clarified tree_ops_ord: ignore markup blocks, proceed like dict_ord;

tuned;

tuned;

more operations;

clarified output: count Tip entries;