Reading lists are OPML documents that point to RSS feeds, like most of the OPML documents you find, but instead of subscribing to each feed in the document, the reader or aggregator subscribes to the OPML document itself.
J. Choi, A. Khlif, и E. Epure. Proceedings of the 1st Workshop on NLP for Music and Audio (NLP4MusA), стр. 23--27. Online, Association for Computational Linguistics, (2020)