You posted a single example (and I am not sure that both return the same results under all conditions, what about making selections in year field?) and there might be several ways to achieve the same, but there are lot of other queries where it's easier or only possible to achieve what you want by using implicite field value definitions ( p() and e() function).
For example, the Help gives a simple example like
=sum( {$<Customer = P({1<Product={‘Shoe’}>} Customer)>} Sales )
returns the sales for current selection, but only those customers that ever have bought the product ‘Shoe’. The element function P( ) here returns a list of possible customers; those that are implied by the selection ‘Shoe’ in the field Product.
I find it a compact and quite easy to understand way of defining your query (having the QV three-color-logic in mind).
And how would you express it in a different way, as easy to read and write?
