A form, or poomsae (also romanized as pumsae or poomse), is a choreographed pattern of defense-and-attack motions.
Taegeuk Yook Jang is often (but not universally) practiced by students of Kukkiwon/WTF-style taekwondo with rank of 3rd geup.
The floor pattern of each taegeuk poomsae then represents three broken or solid lines, called trigrams or gwae (bagua in Chinese).
When these pioneers returned to Korea after the Japanese occupation, they incorporated forms practice into their teaching.
During the 1960s there were several efforts among these pioneers to unify their styles of martial art and create a consolidated set of forms.