Standard dimension names

MINC defines standard interpretations for the following dimension names. Specialized applications are free to define either alternative or supplemental dimensions using other names as desired.

1. xspace - Spatial axis, defined to increase from patient left to patient right.
2. yspace - Spatial axis, defined to increase from patient posterior to patient anterior.
3. zspace - Spatial axis, defined to increase from patient inferior to patient superior.
4. time - Time axis.
5. xfrequency - Spatial frequency axis.
6. yfrequency - Spatial frequency axis.
7. zfrequency - Spatial frequency axis.
8. tfrequency - Temporal frequency axis.
9. vector_dimension - Axis for vector or complex data. If present, this must be the last (i.e. the fastest varying) dimension.