When assigning a variable in one of the flow scopes, referencing that scope is required. For example:

<set name="requestScope.hotelId" value="requestParameters.id" type="long" />
		

When simply accessing a variable in one of the scopes, referencing the scope is optional. For example:

<evaluate expression="entityManager.persist(booking)" />
		

If no scope is specified, like in the use of booking above, a scope searching algorithm will be employed. The algorithm will look in request, flash, view, flow, and conversation scope for the variable. If no such variable is found, an EvaluationException will be thrown.