| Level | Code | Display | Definition |
| 1 | B | beginning |
Condition is tested every time before execution of the service (WHILE condition DO service).
|
| 1 | E | end |
Condition is tested at the end of a repeated service execution. The service is repeated only if the condition is true (DO service WHILE condition).
|
| 1 | S | entry |
Condition is tested once before the service is executed (IF condition THEN service).
|
| 1 | T | through |
Condition must be true throughout the execution and the service is interrupted (asynchronously) as soon as the condition turns false (asynchronous WHILE loop). The service must be interruptible.
|
| 1 | X | exit |
Condition is a loop checkpoint, i.e. it is a step of an activity plan and, if negative causes the containing loop to exit.
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