# concept[].definition
Condition is tested every time before execution of the service (WHILE condition DO service).

# concept[].definition
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).

# concept[].definition
Condition is tested once before the service is executed (IF condition THEN service).

# concept[].definition
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.

# concept[].definition
Condition is a loop checkpoint, i.e. it is a step of an activity plan and, if negative causes the containing loop to exit.