Elements are used to group a related information to print in the script. Sample code in your driver program to call the specified element:
CALL FUNCTION 'WRITE_FORM'
EXPORTING
ELEMENT = 'NEXTPAGE'
WINDOW = 'NEXTPAGE'
EXCEPTIONS
OTHERS = 01.
CALL FUNCTION 'WRITE_FORM'
EXPORTING
ELEMENT = 'REFERENCE'
WINDOW = 'REFERENC'
EXCEPTIONS
OTHERS = 01.