(** @return an associative list format -> string with all possible selection
* formats. Rationale: in order to convert the selection to TERM or PATTERN
* format we need the sequent, the metasenv, ... keeping all of them in a
(** @return an associative list format -> string with all possible selection
* formats. Rationale: in order to convert the selection to TERM or PATTERN
* format we need the sequent, the metasenv, ... keeping all of them in a