Japanese musical culture abounds with seemingly limitless terms to describe every level of music making, from broad general categorizations to labels for numerous sub-genres, with at times complicated and obscure nuances. Ma is recognized in numerous traditional Japanese arts, such as flower arrangement (kado), where the absence of flowers highlight those that are there, a technique similarly employed in traditional garden design. The inclusion of non-Japanese professional performers acknowledges the increasingly prominent position and importance of foreign practitioners for supporting and maintaining Japanese traditions. Japanese traditional music is organized within a ryu, literally translated as "way of doing", but commonly referring to schools; or ie, which translates as "house" or "guilds". Traditional Japanese music is often monophonic, a single voice or instrument, or a group of voices or instruments playing together in unison, or heterophonic, a group of voices playing simultaneous variations on a single melody.