The Left Angle Cross of Prevention is named for Gate 15 and Gate 10, both seated in the G, or Identity, centre. Human Design reads Gate 15, from Hexagram 15, Modesty, as a love of humanity broad enough to embrace extremes, with no fixed rhythm of its own, and Gate 10, from Hexagram 10, Treading, as behaviour that stays true to one's own nature rather than to expectation. It belongs to the Left Angle family, read as transpersonal, a direction practitioners describe as answering less to personal choice than to what circumstance hands the individual, which the cross reads as preventing harm on behalf of others rather than for oneself.
Its design half is Gate 17 and Gate 18. Gate 17 sits in the Ajna and is read as the forming of opinions that want to be organised and offered to others; elsewhere it pairs with Gate 62 in the channel of Acceptance. Gate 18 sits in the Spleen and is read as an instinctive alertness to what is flawed and could be set right; it pairs with Gate 58 in the channel of Judgement.
So the cross joins a wide, extremity tolerant humanity, Gate 15, to conduct true to one's own nature, Gate 10, while beneath it opinions formed in the Ajna, Gate 17, meet a splenic instinct for what needs correcting, Gate 18. The hexagrams are ancient; joining them into one incarnation cross is the modern system's own construction.