(In terms of divisions of the pointer scale). The other point of reversal of an ideal (undamped) swing starting at the zero point of the pointer scale. Since the points of reversal of an ideal swing are located symmetrically about the rest point, the deflection is equal to twice the rest point.
Source:
Orange Book, 2nd ed., p. 36 (https://media.iupac.org/publications/analytical_compendium/)