The present paper aims to analyze the cataloguing of azulejo frames, done for the project Cataloguing Portuguese azulejo patterns initiated in 2011, which can be consulted at Az Infinitum – Sistema de Referência e Indexação de Azulejo (Azulejo Indexation and Referencing System) (http://redeazulejo.letras.ulisboa.pt/pesquisa-az). The importance of the azulejo frame and its independent study, and its connections with the study of the patterns that constitute the remain of the wall and ceiling coverings, has been a crucial concept since the beginning of the project, as it contributes to a better understanding of how pattern azulejo frames were understood throughout the centuries. Also, the systematic cataloguing allows the addition and continuous processing of new data in Az Infinitum, stimulating the emergence of new questions and thus contributing to the production of theoretical knowledge, without never losing sight of its object of study: the work of art in situ.