Allowance: A customary variation from an “exact” measurement, taken for the purpose of anticipated needs.

Apron: The wood trim molding below the windowsill.

Arch apex: The top point of the arch.

Arch window: A window in the shape of a half circle, often placed over a door or other windows for decoration and additional light.

Awning window: Windows that are hinged on top and swing outward to open; usually rectangular and wider than they are long.

Baton: A rod or wand used to hand draw traverse draperies.

Bay window: A group of windows set at angles to each other.

Bow window: A type of window that is curved or semicircular.

Bracket: A metal piece attached to the wall or casing to support a drapery or curtain rod, blinds, or shade.

Carries (aka slides): Small runners installed in the traverse rod, which hold a drapery pin or hook.

Window casing: The wood trim placed around the outside edge of the window recess.

Cathedral window: Slanted window often found with cathedral ceilings; the top of the window follows the slope of the ceiling.

Center support bracket: Additional hidden drapery brackets placed at the center of a long drapery rod when additional support is needed for heavy drapery and to prevent sagging.

Clearance allowance: The amount of space needed between layers of hardware or mounted treatments in order to allow them to function properly.

Clerestory windows: A series of small windows that let in light and air, usually high up on the wall to allow privacy.

Cord cleat: A piece of hardware attached to the wall around which window treatment cords can be secured.

Cord lock: A piece of hardware mounted to the head rail of a shade, through which the operating cords run. When the cords are pulled up, it secures the shade at the desired location.

Corner windows: Windows that meet at right angles at the corner of a room.

Crown molding: Decorative molding placed at a forty-five-degree angle at the ceiling.

Dormer window: An upright window that breaks the surface of a sloping roof.

Double-hung window: The most common style of window; two sashes move up and down.

Eyebrow window: Arched top window with elongated width. Not a true half circle.

Finished drop line: The place where the curtain stops.

Finished length: This is the length after draperies have been made.

Finished width: The actual width after the treatment is finished.

French doors: Usually used in pairs, the doors are made almost entirely of glass panes and open outward. They often open onto a porch or patio.

Front width: The width of the treatment board without returns.

Hopper windows: Hinged from the bottom of the window and open inward from the top, in a triangle shape. The reverse of awning windows.

Inside measurement: Measurement for a treatment so the window facing would be exposed after the treatment is installed.

Inside mount: Location of hardware and treatment are inside a structure, usually a window frame or cornice board. Mounting a treatment wall to wall is also treated as an inside mount.

Inside width: The maximum width of the window recess as measured from the inside.

Mullion: The vertical wood or masonry sections between two window frames.

Muntin: The horizontal and vertical wood strips that separate panes of glass in windows.

Outside measurement: Measurements taken of the outside perimeter of the window frame so that the treatment will cover all window facings.

Outside mount: The hardware for treatment is mounted on the outside of the window on the frame or wall and the treatment is not against any structure on the ends.

Outside width: The measurement of the window from the outside edge of the casing including the window to the other outside casing edge.

Palladian window: A series of windows with an arch on top.

Picture window: A type of window with a large center glass area with usually two smaller glass areas on each side.

Plinth: A square of decorative wood installed at corners of window frames.

Projection (aka return): The distance from the front of the window treatment to the wall where the bracket or board is attached.

Pull cord: The cord on a shade or blind that is pulled to open or close it.

Return: The distance from the front of the window treatment to the wall where the bracket or board is attached.

Sash: The part of a window that opens and closes. It includes a frame and one or more panes of glass. Also the frame and glass of an inoperable window.

Sidelight: A glass panel adjacent to a door, often used at entries for appearance and to provide more light.

Sill: The horizontal “ledge-like” portion of a window casing.

Skylight: A window in the roof that admits light from above. A skylight can be operable or not, some are flat while some are bubble-like.

Sliding glass doors: Large glass doors mounted on tracks that bypass each other.

Template: A tracing made on butcher paper of a hard-to-measure window, arch, or other element in order to create a record of its exact shape.

Vertical stack up: The area taken up by the stack of a shade or blind when it is fully open.

Window recess: The depth of the setback of the window from the wall surface.