When this keyword is present and the calculation performed is a FOM-weighted synthesis, then all reflections with a figure of merit less than f will enter the calculation with only amplitude restraints, but no phase restraints. Use at your own risk. Note that the iteration is started using the phase angles given to the program ( ie. it is not a random-phase seeded calculation), and that the FOMs given are not ignored but are used to adjust how fast the corresponding amplitudes will approach convergence.