There is a distinction between different types of academical dress. Most recently, gowns, hoods and caps are categorised into their shape and patterns by the Groves classification system, which is based on Nicholas Groves' document, "Hood and Gown Patterns". This lists the various styles or patterns of academic dress and assigns them a code or a Groves Classification Number. For example, the Cambridge BA style gown is designated and a hood in the Cambridge full-shape is designated [f1, etc. Because the universities are free to design their own academicals using a wide range of available gown, hood and cap patterns, colours and materials at their and the robemaker's disposal, the academicals of two given universities rarely clash with each other.