SYSTEM FIELDS IN ABAP

What are the system fields? Explain?

The ABAP system fields are active in all ABAP programs. They are filled by the runtime environment, and you can query their values in a program to find out particular states of the system. Although they are variables, you should not assign your own values to them, since this may overwrite information that is important for the normal running of the program.

However, there are some isolated cases in which you may need to overwrite a system variable. For example, by

assigning a new value to the field SY-LSIND, you can control navigation within details lists.

ABAP system fields are always available in ABAP programs. The runtime system fills them according to context. They can then be used in programs to query the system status. System fields are variables but you should always treat them as though they were constants, and only read them. If you change their values, important information for the flow of the program may be lost. In exceptional circumstances, system fields may be overwritten in an ABAP program to control the system – for example, SY-LSIND (for navigating to a detail list).

With one exception the names and data types of the system fields are stored in the ABAP Dictionary in the SYST structure and realized as components of the predefined structure SY in ABAP programs.

The system field SY-REPID is not part of SYST or SY. Instead, every program contains the predefined constants SY-REPID and SYST-REPID, which both contain the name of the corresponding program. Furthermore, there are two predefined types of the same name, SY-REPID and SYST-REPID.

All system fields are addressed using SY field name and their types using SYST field name.

Alphabetical Overview

The following table lists the definitions of the structure SYST in the ABAP Dictionary alphabetically. The character in the first column indicates how you can use the corresponding system field in ABAP programs. Name is the name of the component, Type is the Dictionary data type, and Length is the field length defined in the Dictionary. The Use column shows in which environment the system fields are set. The Description indicates the content.

Name	Type	Length	Use	Description
ABCDE	CHAR	26	Constants	Alphabet (A,B,C,...)
APPLI	RAW	2	Obsolete
BATCH	CHAR	1	Background processing	Program runs in the background
BATZD	CHAR	1	Obsolete
BATZM	CHAR	1	Obsolete
BATZO	CHAR	1	Obsolete
BATZS	CHAR	1	Obsolete
BATZW	CHAR	1	Obsolete
BINPT	CHAR	1	Batch input	Program runs under batch input
BREP4	CHAR	4	Obsolete
BSPLD	CHAR	1	Obsolete
CALLD	CHAR	1	ABAP Program	Call mode of ABAP program
CALLR	CHAR	8	Printing Lists	ID for print dialog function
CCURS	DEC	9	Obsolete
CCURT	DEC	9	Obsolete
CDATE	DATS	8	Obsolete
CFWAE	CUKY	5	Internal
CHWAE	CUKY	5	Internal
COLNO	INT4	10	Creating Lists	Current column in the list
CPAGE	INT4	10	List processing	Current page number
CPROG	CHAR	40	ABAP Program	External procedure call