rexrainbow - So we can create a chess if there is no tile below it now?
Yes, but the other plugins like rex_matcher/rex_slg_movement still checks tiles (lz=0), since tiles are the only necessary chess in each logical position. A logical position is ignored in these plugins if there is no tile placed.
Creating chess without checking tile is used to create chess before tile. For example, designer could save all chess in a logical position, then create them, in any order.