• Pre-Validation - Suppose you want to hide an action in the UI from users who are not members of the current container’s team.

• Post-Select Validation - After a user selects an action, you want to determine whether or not the target object is in a certain lifecycle state before allowing the action to proceed.

• Post-Submit Validation - After a user enters data in the first step of a wizard and tries to navigate to the next step, you want to determine whether or not the information entered on the first step is valid before allowing them to proceed.