Guessing and non-guessing of canonical functions

It is possible to control to a large extent, via semiproper forcing, the parameters (ß, ß) measuring the guessing density of the members of any given antichain of stationary subsets of ? (assuming the existence of an inaccessible limit of measurable cardinals). Here, given a pair (ß, ß) of ordinals, we will say that a stationary set S ? ? has guessing density (ß, ß) if ß = ? (S) and ß = sup {? (S) : S ? S, S stationary}, where ? (S) is, for every stationary S ? ?, the infimum of the set of ordinals t = ? + 1 for which there is a function F : S {long rightwards arrow} P (?) with o t (F (?)) , by a formula without parameters