Any line that moves.

The level, non tapered section of line found behind the belly and taper of a fly line. Most running lines are about 60 feet in length and are attached to the backing on a fly reel.

(also called working line, or lift line, or load line) This is usually 1/4" 7x19 aircraft cable. It can also be 3/16" or sometimes larger. The diameter of the cable is determined by the safe working load designed into the system.

Horses which are referred to as being in the running line are those racing behind the horses who occupy the death seat and one-one position. These horses are one out on the track and are racing with cover.

A thin type of fly line used with a Shooting Head.

a thin line attached to the back of a shooting taper (shooting head) line. May be 20 to 30 pound monofilament, braided nylon, narrow floating or sinking line, or other material. Usually 100 feet in length, it allows the fly fisher to quickly change the type of line being used by interchanging only the head section.