If a piece that cannot retreat or move aside advances across the board until it reaches the other side, it is trapped. This applies to the pawn, stone general, iron general, knight, and lance. This would hardly occur in practice, because all of these but the knight promote to pieces that keep their old moves, and stalemate is a loss for the stalemated player. The situation of the knight is unclear, as it promotes to a piece that does not keep its old moves, and thus there could be a reason to defer its promotion. In chu shogi, which is descended from dai shogi, this situation applies to the pawn, which therefore gets a second chance to promote at the last rank on a non-capture: this second chance can likewise be declined, leaving the pawn as an immobile "dead piece" (死に駒). Whether this rule applies to the knight in dai shogi is uncertain, both because this rule might be a later refinement to chu shogi, and because the Edo-era sources have numerous lacunae when describing the rules of the variants other than sho shogi and chu shogi.