b, a list, of the form {B0,...Bn-1} whose elements are abstract sheaves on X, with rank Bi = ri, for each i. The sheaves should be effective in the sense that cj Bi = 0 for j > ri. The sum of the sheaves should equal f* E; alternatively, one of them can be omitted and it will be deduced from the condition on the sum.
Degree => default value null, the value of this option is ignored
DegreeLift => default value null, the value of this option is ignored
DegreeMap => default value null, the value of this option is ignored
Outputs:
an abstract variety map, the map of abstract varieties g : X → F over S such that g* (Ei+1/Ei) = Bi, for each i, where 0 = E0 ⊆ E1 ⊆ ... ⊆ En = p* E is the tautological filtration on F, and where p : F → S is the structure map of F.