[SciPy-User] Survival vs 1-cdf clarification

For the random variables in scipy.stats, I have a question about the documentation. Does the statement "Survival function (1-cdf — sometimes more accurate)." mean: 1. Survival function (also defined as 1-cdf, and the survival function version is sometimes more accurate). -- or -- 2. Survival function (also defined as 1-cdf, and 1-cdf is sometimes more accurate). Thanks! Olga