-covariates cf = Read file 'cf' that contains covariates values for each dataset
                  input (in both -setA and -setB; there can only at most one
                  -covariates option).  Format of the file
     FIRST LINE  -->  subject IQ   age
     LATER LINES -->  Elvis   143   42
                      Fred     85   59
                      Ethel   109   49
                      Lucy    133   32
        This file format should be compatible with 3dMEMA.

        ++ The first column contains the labels that must match the dataset
            labels stored in the input *.grpincorr.niml files, which are
            either the dataset prefixes or whatever you supplied in the
            3dSetupGroupInCorr program via '-labels'.
            -- If you ran 3dSetupGroupInCorr before this update, its output
               .grpincorr.niml file will NOT have dataset labels included.
               Such a file cannot be used with -covariates -- Sorry.

        ++ The later columns contain numbers: the covariate values for each
            input dataset.
            -- 3dGroupInCorr does not allow voxel-level covariates.  If you
               need these, you will have to use 3dttest++ on the '-sendall'
               output (of individual dataset correlations), which might best
               be done using '-batch' mode (cf. far below).

        ++ The first line contains column headers.  The header label for the
            first column isn't used for anything.  The later header labels are
            used in the sub-brick labels sent to AFNI.