tokens: If the total error is a quadratic sum of two independent errors and , each of which being a linear combination of individual contributing errors , the following condition shall be met to ensure that the budget is compliant with the specification : where ¾ and are the means of the two errors and . ¾ is a positive scalar defined such that for a Gaussian distribution the confidence level encloses the probability given in the specification . ¾ and are the standard deviations of the two errors and . ¾ is the maximum value for the total error , given in the specification . NOTE 1 This condition is extremely conservative and is not an exact formula . See annex A.2.4 for more details . NOTE 2 This applies to the case of “ directional ” pointing errors , in which a requirement is given on the angle between the nominal direction of an axis and its actual direction . In this case and are the Euler angles perpendicular to this axis .