<P> Drops may be hung by various means . Often made of muslin which has been sized and painted, the top may be pressed between two pieces of lumber (a batten) and clamped to a pipe, with a pipe or chain through a hem pocket at the bottom giving it weight to prevent flapping . Some may be grommeted along the top and tied to the pipe with tie - line (usually drapery cord nowadays). A time - honored method of hanging a drop is the roll - drop, in which the bottom of the drop is attached to a round batten . The drop is rolled onto it from the back, and is deployed by rope rigged through blocks (pulleys) to be pulled from offstage to release the tension holding the batten up, thus unrolling it slowly until completely unfurled . </P> <P> There is also a form of drop used in Vaudeville days, which may still be seen in older theaters, called an olio . "Olio" means conglomeration, and these drops were most often roll - drops covered with advertisements from various sponsors, for the audience to view between shows . </P> <P> A cyclorama or cyc is a large curtain, often concave, at the back of the stage that can be lit to represent the sky or other backgrounds . Traditionally white or natural colored cloth, cycs now come in various colors of white, grey, light blue and the green or blue curtains used in Chroma key (greenscreen) work may also be called cycs . </P> <P> With projected scenery, cycs and scrims may be used as drops, by employing either front or rear projection . This was done in a general sense in the 1910s and 1920s by means of painted glass plates in front of lighting instruments, which made sculptured shadows on the cyc to indicate such images as a cityscape or a scary dungeon . (Focus was generalized in the early days; nowadays we have projectors with adjustable lenses .) Lighting instruments (generally ellipsoidals) may also be used to project scenic effects on cycs and scrims, by using gobos, also known as templates or patterns . With an ellipsoidal reflector, the light source is positioned at one focal point of the three - dimensional ellipse, then the pattern - cut metal or glass or other heat - resistant material - is positioned in reverse position so that the light escaping the instrument passes through the pattern first, then through the other focal point and the lenses, and is projected upon the cyc or scrim . </P>

What is the name of the curtains on the side of the stage