Regarding the qform variable, it could be paired with a qform_type or qform_code variable?

Minimally, I would add support for:
- MNI-ICBM (http://www.bic.mni.mcgill.ca/ServicesAtl...)
- Talairach 
- Unknown (Arbitrary coordinates).

It could be defined as a integer:
(ex: 0 = Unknown, 1 = MNI, 2 = Talairach).

NIfTI provides a similar concept with its qform_code (http://nifti.nimh.nih.gov/nifti-1/docume...).

Thanks,

Mathieu