Thank you for the explanation. So the sform*orient will provide information on how to map the i, j, k indices in the BIDS JSON to world space. 

sform_code      1
sto_xyz:1       -1.367200 -0.000000 0.000000 180.621002 
sto_xyz:2       0.000000 1.367200 0.000000 -152.802017 
sto_xyz:3       0.000000 0.000000 2.700005 -65.000862 
sto_xyz:4       0.000000 0.000000 0.000000 1.000000 
sform_xorient   Right-to-Left
sform_yorient   Posterior-to-Anterior
sform_zorient   Inferior-to-Superior

For example, the above information tells us that i maps to RL, j maps to PA, and k maps to IS. 

The PhaseEncodingDirection JSON tag then tells us how the data were collected. So, 'j' will indicate PA acquisition, while 'j-' will indicate AP acquisition, correct?

Thank you for your patience. I want to make sure I'm interpreting this information correctly. 

Jenna