Monteverdi's music might seem to be relatively straightforward in terms of its surviving sources, given that the vast majority of it seems to have been printed during his lifetime. The main exceptions are the late Venetian operas surviving in manuscript, for reasons that will become clear. However, scholars have tended to assume that once print became a standard, and standardised, medium of musical transmission, at least by the 1540s, manuscripts increasingly gained a secondary status. They were still of use in local or individual circumstances – either for practice or presentation – or in the case of music for limited consumption or for particular instrumental repertories (often those not using mensural notation). But these sources and their contents remained marginalised from a mainstream that was more and more defined by printed musical texts. The Census-Catalogue of Manuscript Sources of Polyphonic Music compiled by the Musicological Archives for Renaissance Manuscript Studies at the University of Illinois (1979–88) stops at 1550, and the efforts to deal with later manuscripts on the part of the Répertoire international des sources musicales (RISM) have been famously problematic, though RISM completed its catalogue of printed music by individual composers, 1500–1800, in 1981. Further, print is presumed somehow to grant the musical object some kind of permanence, and also some kind of status as a ‘work’ that therefore can be inserted (or not) into a canon, and into its place in music history.