Ex libris inscription (Ownership inscription)
An inscription that records a book's inclusion in a library, whether private or institutional. Such inscriptions offer valuable evidence of a manuscript's provenance. Bookplates also carry ex libris information. Libraries often employed distinctive labelling and shelving systems, many of which have been identified, and such storage data also provide evidence of provenance.
Michelle Brown, Understanding Illuminated Manuscripts (Malibu, CA: J. Paul Getty Museum in association with the British Library, c1994).