Legal, formal hare coursing has a number of variations in how it is undertaken. Open coursing takes place in the open field, and closed coursing (or park or Irish style) takes place in an enclosure with an escape route. Open coursing is either run as "walked-up" coursing, where a line of people walk through the countryside to flush out a hare, or as "driven coursing", where hares are driven by beaters towards the coursing field. In each case, when a suitable hare appears, a person known as a "slipper" uses a "slip" with two collars to release two dogs at the same time, in pursuit of the hare which is given a head start (known as "fair law"), usually between (). The sighthound is released elsewhere by the handler.