Karate Kata
History
I am not a Karateka, so my experience with their kata is limited. I am also not a Karate historian, so the information provided here will be a simple overview for Taekwon-Do practitioners on their relationship with our patterns.
The Pinan series was developed by Anko Itosu, widely regarded as the father of modern Karate. Itosu took many of Karate's older kata and combined their various unique traits into a series of 5 shorter patterns known as the "Pinan" series. Itosu was a major proponent of introducing Karate to the Okinawan school system, and this series of 5 patterns were a perfect fit for this, as they provided a clear sequence of progression and their length made them easier to teach to larger groups. As Karate was introduced to Japan and then the rest of the world, they became the most widely-practiced patterns in the world.
The Pinan series (later called Heian in some styles) is used today as the colored belt patterns in most modern Karate schools, which then reserve the originals for higher ranking or black belt students. Going by the 1965 order, the Chang Hon patterns seem to line up in certain ways:
-Colored belts draw mostly from the Pinan/Heian series, and follow a general progression:
-#1 - 4 (Chon Ji through Won Hyo) draw mostly from Pinans 1-3
-#5 (Yul Gok) draws mostly from Pinan 4
-#6 (Joong Gun) is an odd exception, drawing from Jitte
-#7 (Toi Gye) draws from Pinans 4 and 5, with some Passai (and Jitte)
-#8 and 9, two of the oldest patterns, Hwa Rang is mostly Pinans 1-3, and Choong Moo is mostly 4-5
-Kwang Gae is based on Hangetsu
-Po Eun is based on Naihanchi/Tekki
-Ge Baek seems to be inspired by Chinto/Gankaku
-Yoo Sin draws heavily from Passai/Bassai-Dai
Every pattern has more than one source, but broad similarities tend to line up in this manner.
Choi's 1965 Kata
Karate kata were practiced in early Taekwon-Do demonstrations alongside the earliest Chang Hon patterns. The following were included in Choi's 1965 book, using an odd mix of their original and Shotokan names:
Pinan/Heian 1-5
Listed in the 1959 program with their Korean names "Pyong an," then in 1965 with their Shotokan name as "HEI-AN."
Passai/Bassai
Listed in 1965 with the Shotokan name as "BAT-SAI" and described as "means to break through the fortress." A pattern is listed in the 1959 program as "Fence Through Forms," and I believe this to be Bassai.
Wanshu/Enpi
Listed in the 1959 program as "Flying Swallow Forms," and in 1965 with the Shotokan name as "EN-BI."
Rohai*
Appears in 1959 as "RO PAE Forms." The 1965 book lists a pattern as "RO-HAI," and the description says that its name "signifies a crane standing on a rock." This name comes from the standing single leg position that appears in some versions of Rohai. In Shotokan, Rohai is called "Meikyo," and does not look much like other versions of Rohai. This led to a very long and confusing search for exactly which version of the pattern is being described in the book. Eventually, after following the directions Choi gives in 1965, it appears that he is in fact describing Gankaku/Chinto, whose Shotokan name is also translated as "crane standing on a rock," and appears to have influenced numerous Chang Hon patterns. This remains a source of confusion.
Kushanku/Kanku
The 1959 program lists a "KONGSANKOON," and 1965 as "KOUH-SHANG-KOUH." Interestingly, neither uses the Shotokan name of "Kanku."
Haihanchi/Tekki 1-3
Listed in the 1959 program as "Riding Form" or "Horse Riding Form," then in 1965 with their Shorokan name as "TET-KI."
Jitte
Listed in 1959 as "Ten Hands Forms," and in 1965 as "JIT-TE"
Seishan/Hangetsu
Not seen in the 1959 demo program. Listed in 1965 as "HAN-GETSU."
Jion
Not seen in the 1959 demo program. Listed in 1965 as "JI-ON."
However, several are not mentioned and clearly influenced Choi's patterns. Unmistakable sections of Unsu and Chinte can be seen in higher level patterns. It's possible that the 1965 book contained only the list of those Choi had learned in his Karate training, or those that were practiced by Choi's Oh Do Kwan.
Personally, I believe that Choi wanted his patterns to contain a complete set of techniques for his martial art, based on the "official" explanation for the addition of Juche, and the mentality that led his students who formed the ATA to replace the Chang Hon with their Songahm poomsae. Because he was interested in techniques, he would not necessarily need to practice a pattern in order to borrow its sequences; he would only need to see a pattern performed in order to want to incorporate its techniques.
Alternatively, these could easily be contributions of the men working with or underneath Choi who had different backgrounds in Karate before forming Taekwon-Do, which could account for stylistic variations appearing different patterns.
Regardless, the study of these patterns' relationship cannot be limited to only those listed in 1965.