From the Interface MapperAssignments pane, right-click, then click New Assignment from the popup menu.
From the Assign to drop-down list, click the field to which you want to assign a value.
Do one of the following:
From the Field 1/Operand 1 drop-down list, select a field.
Type a value into the Field 1/Operand 1 field.
From the Function/Operator drop-down list, click SUBSTRING.
In the Field 2/Operand 2 field, type a number representing the starting position of the extracted string. For example, if you want to extract a string
that begins with the third character of the string, type 3.
In the Field 3/Operand 3 field, type a number representing the total length of the extracted string. For example, if you want to start on the third
character as in the example above, extracting it and the next 5 characters, type 6.
Click OK.
Note:
Fields that are part of an array appear on the Field/Operand drop-down lists with a subscript. The default subscript is the total number of occurrences of the field. To specify a specific
occurrence, edit the subscript in the Field/Operand field. If you want to specify all occurrences, type an asterisk (*) as the subscript.
Any condition defined for the assignment appears in the Assignment Condition box at the bottom of the Assignment dialog box.