Sometimes a directional marker (line arrow) is not the proper marker
to leave -- Non-directional cookies mark a specific place on the line,
but do not give directional information. They are preferred over line
arrows for setting up traverses or circuits because they avoid the
possibility of having directional markers on the line which could point
away from the closest exit, which could be disastrous in an emergency.
They can also offer reassurance during stressful moments. They are a
must at jumps, especially jumps made from points at which no permanent
marker has been installed. Placed on the outbound side of the jump, they
confirm exit direction as divers return to the jump.