In this form of storage, the values of an NDF's array component are stored in their simplest possible form, i.e. as a sequence of pixels in an N-dimensional array with (optionally) a similar imaginary component. This, together with other ancillary information is held in a single ARRAY structure within HDS.
There are no special restrictions on the use of simple arrays and most applications will not need to be aware of the use of this storage form.