Cataloging music manuscripts has been the focus of both German offices for a number of years.
Since June 2010, the database of music manuscripts (which also includes a good amount of printed music) has been available at no cost on the internet as the RISM Online Catalog.
Until 2008, records were published annually on the CD-ROM RISM A/II: Musikhandschriften nach 1600, which was released by the RISM Zentralredaktion.
Although cataloging efforts are primarily directed toward manuscripts that date from the time between 1600 and ca. 1850, entire holdings are recorded when possible, irrespective of date (with the exception of chant manuscripts).
Since cataloging music manuscripts was begun before appropriate computer software was developed, the records that were created conventionally on index cards had to be input into computers in a separate step. This work has since been largely completed. In addition, some collections were published in book form before the appearance of the first electronic edition; these catalogs were also gradually transferred to the RISM database. Today, cataloging music manuscripts is carried out with the computer program Kallisto.
You can read details about the state of cataloging the music manuscripts in German libraries here (the summaries will gradually be filled out with more information about the individual collections):
Index of all collections cataloged by RISM
From 2009 on, the German working group started to publish Catalogues of selected collections in an own series. At any rate the catalogues are excerpts of the data out of the RISM-OPAC and regarding the monthly update of these datas, at least the RISM-OPAC should consulted for further informations. For small collections there are produced copies only for the collection itself.
Musikhandschriften in Deutschland. Kataloge ausgewählter Sammlungen