Directions are vectors that have several uses in ZPL. They are used to create new regions (see Sections 3.5.1 and 5.3.6), and to shift a parallel array reference (see Section 5.3.4).
An example of a definition for a direction of rank two is shown below:
direction east = [0, 1];
northeast = [-1,1];
Directions may be defined in terms of constants or expressions involving
constants. Like regions, directions are not first class objects. They
cannot be modified and cannot be passed as parameters to procedures.