Common SAP system variables

The system has a syst structure that stores system variables. The most common system variables are:
SY-SUBRC: a variable that indicates successful execution after the system executes a command, '0' indicates successful
SY-UNAME: the username of the current user logging into SAP;
SY-DATUM: current system date;
SY-UZEIT: current system time;
SY-TCODE: currently executed ProgramTransaction code
SY-INDEX: Number of times the current loop has passed
SY-TABIX: number of internal tables currently processed
SY-TMAXL: Total number of internal tables
SY-SROWS: Total number of rows on the screen;
SY-SCOLS: Total number of columns on the screen;
SY-MANDT: Current System number (client number)
SY-VLINE: Draw a vertical line
SY-ULINE: Draw a horizontal line