When an unoccupied intersection is surrounded by ships of the same color this is called an eye intersection or ‘eye’. An eye is formed from the withdrawal of a trapped ship or may be formed just from the course of play. A ship may only be placed upon an eye intersection or moved into an eye intersection if it results in the immediate trap of an opposing ship forcing the next play to be a withdrawal. This kind of withdrawal from an inverted double trap position is called a 'gouge'. If no immediate trap will result from occupying the eye intersection, no placement or move into the eye is allowed. Note that a player may knock an opposing ship into an eye even if it creates a trap each for both players. The player whose ship was knocked into the eye must withdraw while the knocker's ship is considered not trapped.