The early fifteenth-century collection of polyphonic pieces in CZ-PU XI E 9 consists of a number of arrangements of well-known works, combined with numerous unica. Among the latter is a rare collection of eight, possibly nine works with Dutch incipits, which make up a substantial part of the Dutch song repertoire of this period. All the works in CZ-PU XI E 9 are textless apart from their incipit. The varied contents of this manuscript, with French, German, Italian and Dutch works, give a fascinating insight into the musical world of the period. This spiral-bound edition, aimed especially at performers, is the first since 1931 and includes additional parts to several works that have survived in other manuscripts and a commentary for each individual work.