Release 10.1A: OpenEdge Development:
Progress 4GL Reference

[ ] Array reference

Square brackets ([ ]) enclose array subscripts ([1], [2], etc.) or ranges (such as, [1 FOR 4]). In a range, you can use a variable for the first element, but the second element must be a constant. The specification [1 FOR 4] causes Progress to start with the first array element and to work with that and the next three elements. Square brackets are also used when specifying initial values for an array. For example, if you define an array variable of extent 3, you might specify initial values as INITIAL [0, 1, 2].