txtDefinition=(abbreviation Op.) Latin for \'93work,\'94 and the publisher\'92s term for the consecutive numbers that came into common usage during the seventeenth century to designate composers\'92 works. Unfortunately, opus numbers have rarely proved to be a reliable guide to chronology. Two publishers often used the same opus number, the composer was rarely consulted, and numbers were sometimes added later. Mozart\'92s music is far better known by its {\uldb K.}{\v 137211} numbers.
