Concertina..............Refers to the Chemnitzer type of concertina.
Key of 'C'...............The note that sounds when the #3 button is played on either side of the concertina while expanding the bellows is the key of the concertina.
Draw.......................Expanding or "drawing" the bellows apart.
Press.......................Collapsing or "pressing" the bellows together.
76 Key....................Describes a Chemnitzer concertina with 16 buttons on the bass side and 22 buttons on the melody side of the instrument. Each button has 2 notes. 16 + 22 x 2 = 76.
104 Key..................Describes a Chemnitzer concertina with 24 buttons on the bass side and 28 buttons on the melody side of the instrument. Each button has 2 notes. 24 + 28 x 2 = 104.
Bass Side ...............The left-hand side of the instrument.
Melody Side...........The right-hand side of the instrument.
Double Reed...........Two reeds for draw and two reeds for press for each button on either side. Usually 1-medium and 1-piccolo on the melody side. Doubles have a total of 208 reeds if they have 52 buttons.
Low Triple............ Three reeds for draw and three reeds for press for each button on either side. Usually 1-low and 2-medium. Sometimes 1-low, 1-medium and 1-piccolo reed set on the melody side. Most low triples have a total of 318 reeds.
High Triple........... Three reeds for draw and three reeds for press for each button on either side. 2-medium and 1-piccolo reed set. Most high triples have a total of 312 reeds.
Quad....................... Four reeds for draw and four reeds for press for each button on the melody side. Usually 1-low and 3-medium. Many made before 1940 had 1-low, 2-medium and 1-piccolo set. Some newer quads have more than 1 set of low reeds. A few have 4 sets of low reeds. Notably in the key of E flat. Quads are "triples" on the bass side except for button #'s 1, 5 and 10 which have 8 reeds per button. (4 draw and 4 press.) Quads have a total of 374 reeds.