A union (collective) catalog of national or international scope can be a combined library catalog that describes the collections of several libraries. According to the 'Encyclopedia of Library and information Sciences' (FEATHER; STURGES, 2003, p. 643), it is an information system with distribution of bibliographic data that “contains not only a list of bibliographic records from participating libraries , but also, of information about the places to identify the properties and collections of the contributing libraries of the system ”. National collective catalogs are instruments that represent bibliographic funds from many collections dispersed in a given country and that can aggregate information services, offer operations such as bibliographic exchange and interaction with users (FEATHER; STURGES, 2003, HIDER, 2003, SUAREZ; WOUDHUYSEN , 2010).