Any P-phase (first letter of phase name is P) with a polarity (C or D) is used, like P, Pg, PP etc. For further processing in FOCMEC, C is labeled C if phase onset is ' ' or I and '+' if phase onset is E. Correspondingly, polarity D is labeled D or -. FOCMEC can also use polarities of SV and SH, but this has not been implemented in SEISAN.
Autimatic polarity determination
Program AUTOPHASE (command ap in EEV) read phase arrivals and polarities. In general it is not recommened to use automatic polarities unless P-phases are very clear. See program AUTOPHASE.
Checking and modifying polarities
Once polarities and/or P-phases are stored in the S-file, the graphical program PLOTPOLARITY (EEV command pol) can modify, add and remove polarities. See PLOTPOLARITY for more details.