Declare opaque- and distinct-type variables
Opaque-type variables hold data retrieved from opaque data types. Distinct-type variables hold data retrieved from distinct data types. If you define a variable with an opaque data type or a distinct data type, the variable can only hold data of that type.
If you define an opaque data type
named point and a distinct data type named centerpoint,
you can define SPL variables to hold data from the two types, as the
following figure shows.
Figure 1. Defining SPL variables to hold opaque and
distinct data types.
DEFINE a point;
DEFINE b centerpoint;The variable a can only hold data of type point, and b can only hold data of type centerpoint.