A large number of instruments from the medieval and renaissance period are unsigned; the practice of adding a signature only became widespread towards the end of the period. In most cases, the exact reason why a maker chose not to sign the instrument is unknown, but several possibilities exist: the instrument may have been a collaborative piece produced in a workshop; the client may have requested that no signature be added; the instrument may be an inferior piece that the maker did not want to be directly identified with; the instrument may be an imitative piece in the style of a well-know maker but by another person; or a signature on the instrument may simply have been defaced or the part of the instrument on which it was engraved lost.