While Action 
The While action executes an action or a block of actions until a specified expression evaluates to false. Since the test of expression takes place before each execution of the loop, a while loop executes zero or more times.
Syntax
While (Boolean-Expression)
Action-Block ...
Example
int index = 0 |
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While (index <= PurchaseOrderSchema:order.itemCount) |
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Execute rule "CalculateDiscountsRule" |
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Assign index = index + 1 |
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