Prior to 1971, Kukkiwon-style taekwondo used a series of eight forms called the "palgwae" forms for color-belt forms. The term "pal-gwae" refers to the eight trigrams associated with the I Ching hexagrams. Symbolically, each form in the palgwae series corresponds to one trigram. Subsequent to 1971, the palgwae forms were deprecated in favor of eight "taegeuk" forms. The term "taegeuk" refers to the principle of the "unity of opposites". Though the movements in the taegeuk forms are different from those of the palgwae forms, each taegeuk form is likewise associated with a corresponding I Ching trigram.