we collected information about several kind of resources
158
Repository
44
Catalogue
36
Dataset
29
Digital Library
22
Software
21
Digital edition
14
Service
12
Ontology
3
Format
3
Project
2
Schema
which deal with symbolic notated music (sheets), descriptive metadata (e.g. artists, genres, cataloguing information), and audio files
207
Symbolic
84
Metadata
48
Media
we mainly relied on resources realized by researchers and targeted to researchers, but we also found other target audiences
the majority of resources offer digitizations of scores and lyrics, followed by audio files and structured data, which are published in several formats
the scale of aggregators of resources (such as catalogues, digital libraries, datasets, repositories, and digital editions) may vary significantly
aggregators gather items by genre, artist, period or country
109Genre96Geographical81Temporal64Artist
generally providers offer different kinds of information related to the musical resources they publish, from general descriptive metadata to more specific data on melody, harmony, rythm etc.
in order to reuse such resources, several open licenses are available - even if most of the providers do not specify it clearly