afni.nimh.nih.gov

Assuming a polort of 5 and 2 runs, the first 6 columns of the
X-matrix will have the model for the 5th polynomial baseline
of run 1, and so they will be all zero for run 2. Similarly,
the next 6 columns would be the 5th degree polynomial model
for run 2, while they would be all zero for run 1.

View those first 12 columns with 1dplot. Assuming that your
X-matrix file is X.xmat.1D, try:

1dplot X.xmat.1D'[0..11]'

- rick