System-Defined Data Objects

System-Defined Data Objects

When you start an ABAP program, some data objects are available automatically and do not need to be declared. System-defined data objects include:

SPACE

The data object SPACE is a constant with type C. It is one character long, and contains a space character. Since SPACE is a constant, it cannot be changed.

System fields

All system fields are named according to the following convention: SY-<name>, where <name> is the name of the individual field. To display a list of available system fields in the ABAP Editor, type SHOW SY in the command line (choose Edit ® More functions ® Command input). The list also includes the data types of the system fields.

The following are examples of system fields:

SY-SUBRC: return code value (zero, if an operation was successful)

SY-UNAME: logon name of the user

SY-DATUM: current date

SY-UZEIT: current time

SY-TCODE: current transaction

System fields are variables and can be changed by the program. However, SAP does not recommend that you do so, because you will lose the information stored in these fields when the execution of your program continues.