D.C. Mun. Regs. tit. 10, r. 10-C2302
"Configuration" means the number, shape, organization and relationship of panes or lights of glass, as defined by sash, frame, muntins, or tracery
"Dimensions" means the size and measurements of both stationary and moveable portions of a window and its applied moldings.
"Fenestration" means the way in which windows are arranged in a facade, including configuration, profile, material, and finish.
"Finish" means the visual characteristics, including color, texture and reflectivity of all exterior materials. A replacement window does not match the finish of a wood window if it is clad with metal or vinyl.
"Frame" means the stationary portion of a window unit, which is affixed to the facade and which holds the sash or other operable portions of the window.
"Glazing" means the glass or other material forming the transparent portion of the window, often in a configuration of separate pieces referred to as panes or lights.
"Match" means a closely approximate, but not necessarily an exact, replication. Tolerances permitted in determining the acceptable level of approximation shall in general be in fractions of inches. In making this determination, the staff considers overall sizes of window openings and proportions of elements making up the window. In all cases, there shall be minimum variation in the distance between the plane of glass and the plane of adjacent exterior surfaces (muntins, sash and frame).
"Meeting rail" means the horizontal portion of sash in a double hung window designed to interlock with the other sash member, usually at the middle of the window.
"Method of operation" means the manner in which a window opens, closes, locks, or functions. If non-operable, a window or window element, such as a sidelight, is identified as "fixed."
"Molding" means a trim piece which introduces varieties of outline or contour in edges or surfaces of window elements such as jambs and heads. Moldings are generally rectilinear, curved, or a composite of curves.
"Mullion" means a vertical primary framing member which separates paired or multiple windows within a single opening.
"Muntin" means a tertiary framing member which subdivides window sash into individual panes, lights or panels. For the purposes of these standards, the term includes lead cames associated with stained glass windows. False muntins or "grids" placed between two sheets of glass are not considered muntins.
"Panning" (also known as "capping" or "wrapping") means a material, usually metal or vinyl, applied to cover the exterior surface of an existing window frame or mullion.
"Profile" means the three-dimensional appearance of a window, particularly as perceived under the conditions of sunlight and shadow. Profile is established by the contours of frame and sash elements, and by the successive depth of recess of the window within the opening, the sash within the frame, and the glass within the sash.
"Sash" means the secondary part of a window, either operable or fixed, which holds the glazing in place. Sash is usually constructed of horizontal rails and vertical stiles, and it may be subdivided with muntins.
D.C. Mun. Regs. tit. 10, r. 10-C2302