Bis is a Latin prefix or suffix designating the second instance of a thing, thus preceding ter. An example in recent modern usage is the ITU-T modem standard from the late 20th century, V.32bis. Bis can also refer to:
Pachelbel's Canon in D major, a piece of chamber music scored for three violins and basso continuo and originally paired with a gigue in the same key, experienced a tremendous surge in popularity during the 1970s.
http://www.geocities.com/Vienna/Studio/7875/Instruments.html. The most generic keys for the trombone are or have been: the soprano in B flat, the alto in G, F or E flat, the tenor in A or B flat, the bass in B flat\F, D or G, and the contrabass in BB flat.