The RISM library abbreviations, or sigla, are used for identifying locations of musical manuscripts.
Gesamtverzeichnis (RISM Library Sigla.
Complete Index), which appeared in 1999, has been available in a regularly updated version on the RISM website since 2006 and in a searchable database online since 2011.
[1] The complete list is very long (see pdf).
Only a selection of major source locations are listed here: