Catalogue Number is a number assigned to an object or artwork in a museum, gallery, or a collection center basically to get some information about the piece of art. However, the criteria or basis of assigning the number and its purpose may vary.  In some museums, libraries, art galleries, and archives, the catalogue number is the unique identifier number that was assigned to a piece of art at the time of its initial acquisition. It is same as the accession number when used in this sense. In others, it may be a number assigned to the article based on its class. Here, the collection number is used to describe the artwork. Again, collection number can also be the number that is assigned to an object in the catalogue of an exhibition or any other publication.