The following table lists the system fields for the date and time.
| System field | Content |
| sy-datlo | Date in the current user's time zone. |
| sy-datum | Local date of the ABAP system. |
| sy-dayst | Indicator for summer time. During summer time, "X", otherwise " ". |
| sy-fdayw | Factory calendar weekday. "1" for Monday, ..., "5" for Friday. |
| sy-timlo | Time in the current user's time zone. |
| sy-tzone | Time difference from the UTC reference time in seconds, ignoring summer time. |
| sy-uzeit | Local time of the ABAP system. |
| sy-zonlo | User's time zone. |
The values of all system fields in this table are implicitly set when the program is started, every time a screen layout of a screen is sent, and when the internal mode is set. The GET TIME command explicitly updates the system fields, except for sy-dayst, sy-fdayw and sy-tzone.
With the exception of sy-datlo and sy-timlo, all system fields refer to the local date and time of the current SAP system. The ABAP runtime environment clock is synchronized with the database server clock at regular intervals in order to calculate the local time of an ABAP system. During the synchronization process, the ABAP runtime environment clock is set to the database server clock. Because this happens on all application servers in an ABAP system, the ABAP runtime environment clock is synchronous with the clocks on all other application servers and with the database system clock, and thus shows the local time of the entire ABAP system. The time zone on which the local time of an ABAP system is based is the only entry in the database table TTZCU.
The content of sy-zonlo is taken from the user master record of the current user. The values of sy-datlo and sy-timlo are calculated from sy-datum and sy-uzeit and from the time zone of the ABAP system for the time zone in sy-zonlo. If the user master record does not contain a time zone, or if it contains an invalid or an inactive time zone, sy-datlo and sy-timlo are set to the values of sy-datum and sy-uzeit. All valid time zones are defined in table TTZZ.