How to define types and data objects

REPORT CHAP0101.

* Elementary type character, length 20
DATA CUSTOMER_NAME(25) TYPE C.

* Non-elementary type
TYPES T_NAME(25) TYPE C.
DATA NEW_CUSTOMER_NAME TYPE T_NAME.

* Reference to a data object
DATA VENDOR_NAME LIKE CUSTOMER_NAME.

* Record
DATA: BEGIN OF BOOKING,
ID(4) TYPE C,
FLIGHT_DATE TYPE D,
NAME LIKE CUSTOMER_NAME,
END OF BOOKING.

* Internal table
DATA BOOKING_TABLE LIKE BOOKING OCCURS 100.