Accessory stops – Special effect stops found on most table organs up to the mid-18th century; most common are drum (Sp. tambor) and little birds or nightingales (Sp. pajaritos); also known as toy stops.

Bellows – Apparatus separate from the organ with a base and top of wood and side pleats of sheepskin; it is raised and lowered to direct air under pressure to the windchest via a wind trunk; the most common forms are wedge bellows, raised from one end in older organs, and in later organs as reserve bellows with parallel pleats (Sp. fuelle).

Divided registers – Wind chest construction typical of Spanish baroque organs in which the sliders are divided at middle c’/c#’ and may have different stop lists on either side; the corresponding lower bass half of the keyboard is from middle c and below (Sp. bajo), the upper soprano half from c# and above (Sp. tiple); each half is controlled by stop knobs or slider pulls on either side of the keyboard, allowing the organist the possibility of choosing a different sound for each hand. A few table organs may have one or two sliders divided b/c’ even if the majority are divided c’/c#’ (Sp. medio registro, registros partidos).

Drawknob –Wooden knob (Sp. pomo) at the end of a shaft on the façade of stationary organs which is pushed or pulled to activate or cancel the sound of the register to which it is connected by moving a perforated slider under the pipes; in Oaxacan organs “on” position may be pushed or pulled (Sp. tirador de registros).

Foot – Measure of the speaking length (from mouth to top) of the longest principal pipe used to categorize organs and determine its pitch. Large Oaxacan organs are eight-foot (8´), medium are four-foot (4´), and small are two-foot (2´); an eight-foot pipe sounds at unison pitch, a four-foot pipe an octave higher, a two-foot pipe two octaves higher. (Sp. pies).

Hips –Rounded protuberances on the sides of the lower case of Oaxacan-built stationary organs, distinguishing them from organs with straight sides built elsewhere in Mexico; hips on organs are documented from the late 17th to late 19th centuries but probably originated earlier, and their purpose seems to be decorative rather than functional; they may be integrated into the lower case construction or hung on the sides, symmetrical or with a high bulge, small and merely symbolic or extravagant; their profile may be repeated across the façade as a decorative detail (Sp. caderas).

Horizontal trumpets – A rank of pipes placed horizontally rather than vertically, projecting from the front of the organ case above the key desk and characteristic of stationary Iberian-style baroque organs; an 8´ rank of trumpets may correspond to the entire keyboard or to its soprano half (Sp. clarines); because of the length of the lowest 8´pipes, a 4´ register is more common in the bass half of the keyboard. This stop is usually placed in the façade but sometimes may be found inside the case (Sp. bajoncillo).

Key desk – The recessed square around the keyboard, including the register knobs if they are on the sides of it and not projecting from the façade of the organ (Sp. ventana).

Mechanical action - Key action in which the keys are connected by wooden trackers to the pallets which open to admit air from the wind chest into the pipe; pressing the key opens the pallet and releasing the key allows it to shut by means of a spring (Sp. tracción mecánica).

Mixture –A register with multiple ranks of the same tone; Roman numerals indicate the number of ranks of pipes involved such as Quincena IV (Sp. mixtura)

Pallet – A valve in the wind chest of the organ which is opened to admit air to the channel of a particular note; the air then passes to the pipe depending on whether the slider for a stop under its pipes is in open or closed position; each pallet is connected to its corresponding key by a tracker and is opened by pressing the key (Sp. ventilla).

Pallet box – The structure at the base of the chest which stores the wind under pressure; it houses the row of pallets, each corresponding to a separate key (Sp. arca de viento).

Pipe – The basic element of the organ (Sp. tubo); wind is blown through it to produce the sound of a single note; the two basic types are flue pipes (Sp. tubos labiales), open or stopped (covered at the top), which may be of metal or wood, and metal reed pipes (Sp. lengüetas)

Pipe shade – Decorative wood carvings which fill in the empty space above the groups of façade pipes and keep them from falling forward (Sp. celosía).

Pitch – Based on the sound of a above middle c, Oaxacan organs were pitched low, between 392 and 415 Hz (hertz or frequency of vibrations); many were later modified, (i.e., tops of pipes were cut to shorten them) in the late 19th or early 20th century, to correspond to modern pitch at 440 Hz. (Sp. diapasón, afinación).

Principal – The tonal base and fundamental sound of the organ on which all the other registers are based; the pipes of the principal register usually stand in the façade of stationary organs; these may be 8´, 4´, or 2´ depending on the size of the case. (Sp. flautado mayor).

Rackboard – A thin horizontal perforated board, often covered with sheepskin, placed on wooden supports to stand above the toeboards; it holds up the pipes in place on the chest and prevents them from falling over (Sp. panderete).

Register – Row or ranks of pipes (Sp. hileras) which produce a homogeneous sound (Sp. registro).

Registration – The art of choosing and combining stops to produce the desired sounds in a specific organ that will properly enhance the music being played (Sp. registración)

Roller board – A wooden vertical panel above and behind the keyboard with a series of horizontal wooden rods or rollers (Sp. molinete) connected to the keys by trackers, and which transfers the movement of the keys to the pallets of the wind chest (Sp. tablero de reducción).

Short octave – Keyboard design typical of the 15th to mid-19th centuries in which the lowest octave of the keyboard is not chromatic, but is shortened by the omission of C#, D#, F#, and G#; E corresponds to C, F# to D, and G# to E; typical of Oaxacan organs until around 1840 (Sp. octava corta).

Slider – Perforated wooden slat inside the wind chest which is connected to the mechanism of the registers; it slides back and forth to allow or prevent air from entering the row of pipes above it, based on whether its holes are aligned with those of the wind chest below and the toe boards above; in stationary organs, registers are selected by pushing and pulling the stop knobs or in some cases levers on the façade; in table organs, the ends of the sliders protrude from the sides of the case and are similarly pushed and pulled (Sp. corredera).

Stationary organ – Instrument in fixed position on the floor with an 8´ or 4´ principal; the register draws are usually but not always on the façade (Sp. órgano fijo).

Sticker or pin action – Key action typical of 18th century Oaxacan table organs and a few 4´ stationary organs; when a key is depressed, it pushes on a wooden rocker or backfall set in splayed fashion under the keyboard (serving the function of a horizontal tracker); these push on small wooden pins to open the appropriate pallet (Sp. tracción de balancines).

Table organ – 2´ or 4´organ which sits with its bellows (behind the pipes) on a table; the end of the sliders for controlling the registers protrude from the sides of the case; the smallest Oaxacan organs were originally used in processions but are now in fixed positions (Sp. órgano de mesa).

Temperament – System of musical tuning used to space intervals between half tones of the keyboard in order to favor certain keys over others; meantone temperament (Sp. temperament mesotónico) is common in Oaxacan organs into the 19th century; 1/4 comma meantone temperament is the purest in terms of frequencies, but 1/6 comma has less of an “edge” and allows the organist to play in more tonalities. Around the mid-nineteenth century the temperament of Oaxacan organs began to approximate equal temperament in which each half tone interval is equal and all tonalities may be used (Sp. temperamento igual).

Toeboard – A long pierced wooden board which sits above the sliders and covers the top of the wind chest; the toe or foot of a pipe stands in each hole and is held firm and prevented from falling over by a pipe rack; the rows of holes correspond to the rows of pipes (Sp. tapa).

Tracker – A long thin vertical piece of wood, usually rounded but sometimes rectangular, which connects the key of an organ to its pallet, either directly or via a roller connected to a roller board; pressing the key opens the valve to admit air to the pipe (Sp. varilla).

Trundle – A rotating rod with arms which transfers motion from the stop knob rod to the slider (Sp. molinete de registro, árbol giratorio).

Tuning –The adjustment of each pipe to sound at the correct pitch; open flue pipes are tuned by changing the length; metal stopped flue pipes are tuned by adjusting the ears (Sp. orejas) on the sides of the mouth and wooden ones by adjusting a stopper at the top; reed pipes are tuned by changing the length of the vibrating metal tongues by moving a tuning wire (Sp. afinación)

Voicing –The process of adjusting the various parts of a pipe so as to produce the desired uniform sound; pipes in the same rank must be consistent in their attack (the first moment the pipe sounds), the tone quality or color, and the volume or strength of the tone; voicing is the final, most complex and artistic step in organbuilding or restoration and provides or restores to the organ its particular tonal character (Sp. armonización).

Wind chest – Wooden box inside the organ which includes the pallets, sliders, toeboards and other wooden components; it stores the air from the bellows under pressure and distributes it to the pipes, according to the stop selected and the key pressed, to make them sound (Sp. secreto).

Wind trunk – A large wooden square or rectangular conduit which conveys the air from the bellows to the wind chest (Sp. portaviento).