4G. array ([])
--------------
<var>[<indexexp>] (is a <varexp>)
This operator reads the value from the array <var> points to, with
index <indexexp>. The index may be just about any expression.
Note1: "[]" is a shortcut for "[0]"
Note2: with an array of n elements, the index is  0 .. n-1
Examples:

a[1]:=10           /* sets second element to 10 */
x:=table[y*4+1]    /* reads from array */
x.y[3]             /* accesses array in an object */