The default options assume the epi and anat datasets start off fairly close,
as is normally the case when the epi dataset closely precedes or follows an 
anatomical dataset acquisition. If the two data are acquired over separate
sessions, or accurate coordinate data is not available in the dataset header
(as sometimes occurs for oblique data), various options allow for larger
movement including "-cmass cmass", "-big_move","-giant_move",
"-ginormous_move", and -align_centers yes". Each of these options
is described below. If the datasets do not share the same
coordinate space at all, it may be useful to use the "-ginormous_move", 
"-align_centers" options or run @Align_Centers script first.