The try filter matches a position if the position represents a top-level white try. We define this as meaning that there is precisely one white move leading to that position that is not a primary move.

The try filter can be (and in fact is) defined as an abbreviation for the following CQL code:

  1==find <-- quiet all {btm secondary}

In a sound study without duals, every position for which try is true is worse for white than the study stipulation. Thus, in a win study, every such position is drawn or lost for white; in a draw study, every such position is lost for white.

The try filter is typically used with echo to help remove false positives.