A comma-separated list of values which call for matches on different subsets of the supplied parameters:
ORNULL will result in DLN=x and (NAME=n and (DOB=d or DOB=null))
ORNULL,ORID will result in DLN=x OR (NAME=n and (DOB=d or DOB=null))
ORID will result in DLN=x OR (NAME=n and DOB=d)
ORID,FLTALL will result in (DLN=x and DOB=d) OR (NAME=n and DOB=d)
ORID,FLTALL,ORNULL will result in (DLN=x and (DOB=d or DOB=null)) OR (NAME=n and (DOB=d or DOB=null))