Every HDS object has a shape or dimensionality. This is
described by an integer (the number of dimensions) and an integer
array (containing the size of each dimension). A scalar (for
example a single number) has, by convention, a dimensionality of zero;
i.e. its number of dimensions is 0. A vector has a
dimensionality of 1; i.e. its number of dimensions is 1, and
the first element of the dimension array contains the size of the
vector. An array refers to an object with 2 or more dimensions;
a maximum of 7 dimensions are allowed. Objects may be referred to as
scalar primitives or vector structures and so on.
HDS [1ex