The mask bulk solvent correction was applied using all data.

An improved bulk solvent correction will be included in a future version of REFMAC.

However, the overall positive effects of the bulk solvent correction on the scaling and thus on the calculation of electron density difference maps appears to be overwhelming.

The systematic deviation of the calculated protein structure factor amplitudes without a bulk solvent correction from the observed structure factor amplitudes is clearly visible.

This is useful if you want to calculate hydrogen contributions, add in an anisotropic heavy atom, add in a bulk solvent correction, which has been calculated somewhere else.