FactorSquareFree[poly] pulls out any multiple factors in a polynomial.
FactorSquareFree[poly, Modulus->p] pulls out multiple factors modulo a prime p.
FactorSquareFree[poly, Extension->Automatic] extends the coefficient field to include algebraic numbers that appear in the coefficients of poly.
See Section 3.3.4.
New in Version 1; modified in 3.
See also: FactorSquareFreeList.