The Right Angle Cross of Explanation is named for Gate 49 and Gate 4. Human Design reads Gate 49, from Hexagram 49, Revolution, sitting in the Solar Plexus, as principle, the sense of what is acceptable, which decides whether an arrangement continues or is broken off; and Gate 4, from Hexagram 4, Youthful Folly, sitting in the Ajna, as the mental habit of offering answers and hypotheses to questions still open. It belongs to the Right Angle family, the largest of the system's three, read as a personal destiny that answers mainly to the individual's own choices.
Its design half is Gate 43 and Gate 23, which are in fact the two ends of one channel, Structuring, so the unconscious half is a single circuit rather than two separate pressures. Gate 43 sits in the Ajna and is read as the sudden inner knowing that arrives whole and resists easy explanation. Gate 23 sits in the Throat and is read as the voice that turns that knowing into language others can take in.
So a chart carrying this cross judges what is acceptable while offering hypotheses on its surface, while beneath it a whole sealed channel already supplies both the insight and its telling. The same pair, reversed, also underlies a Right Angle Cross of Explanation under the opposite ordering, and the same two gate pairs recur in two further role arrangements. The hexagrams are ancient; grouping four of them into one personal cross is the modern system's own construction, dated to 1987.