MINC dimensions may have either *regular* or *irregular*
spacing. Regularly-sampled dimensions are sampled at a constant
interval, while irregularly-sampled dimensions are sampled at
arbitrary positions along the axis.

Because regular dimensions are sampled at a constant interval, they are fully defined by their origin and step size. Therefore, the dimension variable for a regular dimension contains no meaningful data.

For an irregular dimension, the value of the dimension variable must be a vector with a length equal to the number of sampled points along the dimension. The value of the vector at a given index gives the value of the dimension at that sample point.

Robert VINCENT 2005-05-10