Active Panel - Primary operating door panel.
Aluminum Surround - The aluminum frame around a screen or energy panel.
Apron - A piece of casing or decorative trim installed against the wall immediately beneath the stool of a window.
Argon Gas - A colorless and odorless gas used to fill the airspace between insulating Low E glass. The addition of argon greatly increases the insulating performance of the Low E glass.
Assembly - Single units mulled together.
Astragal - A moulding applied to one stile of a French Door, Sliding French Door or French Casemaster window unit which the other door panel or window sash strikes. Usually head and footbolt devices will be found on the astragal side.
Authentic Divided Lites (ADL) - Also known as True Divided Lite. Permanent stationary muntins and bars separate the glass in a window or door sash to give the sash two or more lites of glass.
Awning Window Unit - A combination of frame and sash, hinged at the top of the vertical jambs which allows the unit to pivot from the top with the sash opening to the exterior of the building.
Balances - A block and tackle system used in the jamb liner of double hung or single hung units.
Bars - A narrow rabbeted, horizontal or vertical sash or door member in an authentic divided lite unit, extending from rail to rail or stile to stile along the total length or width of the glass opening.
Bay Windows - A series of windows installed in a bay which is two flanker units and a center sash; a bay may be an arc or a polygon; when a bay is or closely approaches an arc, the window is termed a bow. See Bow Windows.
Blindstop - The frame member on a double hung window located between the jambs and the casing. The blindstop forms a rabbet that supports either a storm sash or screen.
Bow Windows - A series of adjoining window units, installed on a radius.
Brick Mould Casing BMC - An exterior moulding of window and door frames that abuts the exterior facing material of the structure. The casing serves as the boundary moulding for brick or other siding material and also helps to form a rabbet for screens and/or storm sash or a combination door.
