For throws, I use Toshiro Daigo's book Kodokan Judo Throwing Techniques published by Kodanasha International, Tokyo 2005. It specifically addresses some of the arcane points of Kodokan classification that distinguish what is considered one throw versus another. This book is mostly up to date. Is there a similar canonical resource that covers mat (pins, chokes, armlocks) techniques? For example, I was just informed that ude garami can be done against a straight arm. I previously would have called that an ude hishigi ude gatame.
Of the materials published by the Kodokan, the two which describe the classification of Katame-waza in most detail are:
- Kodokan Judo: The Essential Guide to Judo by Its Founder Jigoro Kano (1997)
- Kodokan Judo Katame Waza: Various techniques and their names (1994) (video)
Both works demonstrate and list the points of distinction of each technique and their common variations. The video series demonstrates the straight arm variant of ude-garami. While Kano's book includes examples of three variations of ude-garami, it unfortunately does not include the straight arm variant.
Note however that Kano doesn't claim that the examples in this text are exhaustive, making the following caveat:
The katame waza introduced here are the ones most frequently used in randori and competition.
History of Kodokan Katame-waza classification:
01/02/1985: Adds classifications for
• Sode-guruma-jime, Kata-te-jime, Ryo-te-jime, Tsukkomi-jime, Sankaku-jime
• Ude-hishigi-ashi-gatame, Ude-hishigi-te-gatame, Ude-hishigi-sankaku-gatame
01/04/1997: Renames hon-kesa-gatame to kesa-gatame
01/04/2017: Adds classifications Ushiro-kesa-gatame, Uki-gatame, Ura-gatame