which refers to the recorder in C5 (soprano) as the descant and the recorder in F4 (alto) as the treble. As conventions and instruments vary, especially for larger and more uncommon instruments, it is often practical to state the recorder's lowest note along with its name to avoid confusion. Notation Modern recorder parts are notated in the key they sound in. Parts for alto, tenor and contrabass recorders are notated at pitch, while parts for sopranino, soprano, bass, and great bass are typically notated an octave below their sounding pitch. As a result, soprano and tenor recorders are notated identically; alto and sopranino are notated identically; and bass and contrabass recorders are notated identically. Octave clefs may be used to indicate the sounding pitch, but usage is inconsistent. Rare sizes and notations include the garklein, which may be notated two octaves below its sounding pitch, and the sub-contrabass, which may be notated an octave above its sounding pitch. Historical recorders The earliest known document mentioning "a pipe called Recordour" dates from 1388. Historically, recorders were used to play vocal music and parts written for other instruments, or for a general instrument. As a result, it was frequently the performers' responsibility to read parts not specifically intended for the instrument and to choose appropriate instruments. When such consorts consisted only of recorders, the pitch relationships between the parts were typically preserved, but when recorders were combined with other instruments, octave discrepancies were often ignored. Recorder consorts in the sixteenth century were tuned in fifths and only occasionally employed tuning by octaves as seen in the modern C, F recorder consort. This means that consorts could be composed of instruments nominally in B, F, C, G, D, A and even E, although typically only three or four distinct sizes were used simultaneously. To use modern terminology, these recorders were treated as transposing instruments: consorts would be read identically to a consort made up of F3, C4, and G4 instruments. This is made possible by the fact that adjacent sizes are separated by fifths, with few exceptions. These parts would be written using chiavi naturali, allowing the parts to roughly fit in the range of a single staff, and also in the range of the recorders of the period. (see Renaissance structure) Transpositions ("registers"), such as C3–G3–D4, G3–D4–A4, or B2–F3–C4, all read as F3–C4–G4 instruments, were possible as described by Praetorius in his