The Right Angle Cross of Tension is named for Gate 39 and Gate 38. Human Design reads Gate 39, from Hexagram 39, Obstruction, sitting in the Root, as provocation, the pressure that stirs feeling in other people to discover whether there is any spirit in them; and Gate 38, from Hexagram 38, Opposition, sitting in the same centre, as the fighter, the drive to oppose and the need to discover something worth opposing. It falls in the Right Angle family, and practitioners describe that group as the personal one, a direction shaped by what the individual decides.
Its design half is Gate 21 and Gate 48. Gate 21 sits in the Heart or Will centre and is read as the will to control material life on one's own terms; it pairs with Gate 45 in the channel of Money. Gate 48 sits in the Spleen and is read as depth, a well of instinctive knowledge not yet useful, and a fear of being inadequate; it pairs with Gate 16 in the channel of the Wavelength.
So a chart carrying this cross provokes and fights on a shared Root surface, while beneath it a will to control answers to an unspent depth it cannot yet trust. The personality pair recurs, held instead in the Left Angle family, as the Cross of Individualism, though that cross pairs the same provocation with different design gates entirely, so no true sibling of this exact four gate set exists elsewhere in the system. The numbers are inherited from the I Ching; reading them as one cross belongs to the modern reading, not the classical one.