X(1), X(2)

These lines shows information about the cross-reference values. Every cross-reference value must have a unique order number. X(1) corresponds to the cross-reference value with order number 1; X(2) corresponds to the cross-reference value with order number 2.

X(1) in this case is the value of the DOB field (file #662100, field #.03), which is stored in the first subscript (Subscr 1) after "C" in the index. The forwards designation indicates that lookups will traverse this subscript in a forwards direction. (This is the Collation property of a subscript, and will be discussed further in Lesson 3).

The subscript number for a cross-reference value need not equal the order number. In fact there may be times when you'd create a cross-reference value that has no subscript number. In that case, even though the value isn't stored in the index, you can still refer to it via X(order#) in the cross-reference logic. (You'll see an example of this in Lesson 5.)