[phenixbb] omit map with phases

Hi, When I am using phenix.autobuild to calculate an SA_omit map, I found out the phenix.autobuild automatically used the phases in my mtz file. How does phenix.autobuild use the phases? and is it a good idea to use phases in omit map calculation? and what kind of phases are preferred, experimental phases, phases after density modification, and phases after multi-crystal averaging? Thanks. -- Jianghai