Each "TrkM..." file contains tracked magnetograms, one each minute, bundled into one day specified by the file name "yymmdd" e.g. 020120 = 20th January 2002

TrkM_020120.tar.gz

The vector field extrapolations from MDI line-of-sight observations, averaged for each hour over 9 days are in the file,

B_MDI_vect.tar.gz