5.7.5 Subscripted Variables
  A subscripted variable is a floating-point, integer, packed
  decimal, RFA, or string variable that is part of an array.
  Chapter 7 describes arrays in more detail.

  An array is a set of data organized in one or more dimen-
  sions. A one-dimensional array is called a list or vector . A
  two-dimensional array is called a matrix . Arrays can have
  up to 32 dimensions.

  When you create an array, its size is determined by the
  number of dimensions and the maximum size, called the
  bound , of each dimension. Subscripts begin by default with
  0, not 1. That is, when calculating the number of elements in
  a dimension, you count from zero to the bound specified.

  The following DECLARE statement creates an 11 by 11 ar-
  ray of integers. Therefore, the array contains a total of 121
  array elements.
  DECLARE INTEGER My_array (10, 10)

  There are many applications where you need to reference
  data for a particular range of values. You can specify a lower
  bound other than zero for your arrays. The following exam-
  ple declares an array containing the birth rates for the years
  from 1945 to 1985:
  OPTION TYPE = EXPLICIT, &
            SIZE = REAL SINGLE
  DECLARE REAL Birth_rates(1945 TO 1985)

  Subscripts define the position of an element in an array; the
  expression Birth_rates (1970) refers to the 26th value of the
  array Birth_rates . For more information about arrays, see
  Chapter 7.