The 12 categories = the 12 quintets
The card game exists of 12 different categories, which are chosen from different sources*, old and new, about the Taoist five element theory.
Most categories are super suitable for learning zen shiatsu, acupuncture, acupressure, or other kind of studies derived from Traditional Chinese Medicine (TCM).
The 12 categories are mentioned in the left column, in bold:
Each category holds all five elements: Wood, Fire, Earth, Metal and Water.
When playing the card game, we call this a quintet. The goal is to collect the most quintets.
* a side note: in the card game sometimes the choice was made to not follow the absolutely core TCM information, like the Huang Di Nei Jing (The Yellow Emperor), as the card game is a result of a graduation process for Zen Shiatsu studies.
The choices were subject to the input of other writers, teachers and personal experiences and preferences. And some of the choices are made for the practical use of the game, especially for newbies and non-native English speakers.
Of course, there is a lot of respect to the ancient knowledge.