Water AKA The Abysmal
This trigram is the symbol of containment in the bottom position of a hexagram, and control when in the top position of a hexagram. One of the six 'mixed' trigrams, symbolic of the interaction of degrees of yin and yang.
In the IDM template it is representative of contractive bounding and thus an overall bias to making of distinctions through the establishment of boundaries separating inner and outer. (e.g. socialization through structured education). In emotions the link is to disgust and so the focus on 'us' from 'them', on socialiation and rejection of all not 'socialised'.
There is a focus here on values, on 'them' vs 'us' and a sense of determination based on morality (right/wrong) vs the complement trigram of Fire that is more 'true/false' in perspective.
In Chinese Five-Phase theory, Water is linked to the concept of WATER and so the concept of CONSUMPTION - a focus on the literal taking-in of food but also the metaphoric form as reflected in socialisations, learning and living through, conforming to, the 'party line'.
In the Myers-Briggs/Keirsey systems of persona classification it is linked to XSFJ/Conservators and is mostly concerned with security seeking through creating boundaries (e.g. Protectors, Provision of necessities).
The numeric link is with rational numbers. (distinction of parts). The Peircean Category is Secondness as Passive/Implicit RESPONSE with its emphasis on asserting values.