rigging. Otherwise it relies solely on the motor power of an electric hoist to fly a line set. Together, a series of parallel line sets regularly spaced up and down stage, commonly at , , or centers, comprise the bulk of most fly systems. Theatrical rigging systems are made up of hemp, counterweight and/or automated line sets able to serve various functions. Line set functions Line sets are typically general purpose in function, meaning they can perform any number of functions which vary depending upon the requirements of a particular theatre production. For example, a general purpose line set can usually be quickly transformed into a drapery or scenery line set, but converting a general purpose line set into an electrical line set is more involved. When a line set has a predetermined, relatively permanent, function it is known as a dedicated line set. Line set functions include: Drapery and track line set Line sets often suspend theater drapes and stage curtains such as travelers, teasers (a.k.a. borders), legs, cycs, scrims and tabs, as well as associated tracks, in order to mask and frame the stage and provide backdrops. Line sets are sometimes dedicated to particular draperies, such as the main (grand) curtain and main border (valance) that mask the proscenium opening, but drapery locations can often vary. Scenery line set In many stage productions, theatrical scenery is mounted to line sets in order to be flown in and out so as to quickly change set pieces during the course of a performance. For example, painted soft and hard flats (e.g., muslin drops) and are commonly used to depict settings. Also, three-dimensional sets (e.g., box sets) may be flown. Electrical line set Electrical line sets, commonly called electrics, are used to suspend and control lighting instruments and, in many cases, microphones and special effects equipment as well. Electrics may be temporarily "wired" with drop boxes (electrical boxes with outlets) or multicable fanouts dropped from the grid or draped from a fly gallery, or permanently wired with connector strips (specialized electrical raceways). There are normally at least three electrical line sets provided above the stage, with one just upstage of the proscenium wall, one mid-stage, and one just downstage of the cyclorama. Additional electrics are typically desirable. Permanently wired electrical line sets are known as dedicated electrics, fixed electrics or house electrics. In addition to providing dimmed and switched outlets for