2.3.1 Aggregate Variables

 A variable (section 2.3) that contain an aggregate data value (section 2.1.1) is an aggregate variable. An aggregate variable consists of dependent variables each one corresponding to an element (section 2.1.1) of its current aggregate data value. The data value contained by each dependent variable is the corresponding element data value of its containing aggregate data value. In some situations, a dependent variable itself holds an aggregate data value with its own dependent variables. Dependent variables do not have names; instead they are accessed using index expressions for arrays or member access expressions for UDTs.

When a new data value is assigned to a dependent variable, the aggregate variable holding this dependent variable’s containing aggregate data value has its data value replaced with a new aggregate data value that is identical to its previous data value except that the element data value corresponding to the modified dependent variable is instead the data value being stored into the dependent variable. If this containing aggregate data value is itself contained in a dependent variable this process repeats until an aggregate variable that is not also a dependent variable is reached.