Hi Justin, that a good question !
there is a difference between the 2; let me explain:
Let's suppose we have a Dimension called Dim containing these values:
A
B
C
D
1) sum({<Dim=-{'A'}>}Measure)
is like writting :
sum({<Dim={*}-{'A'}>}Measure)
which means, sum Measure of All the values of Dim but the value 'A'.
<=> All Dim's values minus A no matter the selection made in the filter Dim
So, even if u select value B for exp; it will always return the sum of B C and D
2)sum({<Dim-={'A'}>}Measure)
return the sum measure of what u select minus A
which means, if we select nothing, it returns the sum of B C and D
But if we select, B; it return only B
if we select A and B and C, it will return B and C
<=> what u select minus A
Hope that was clear?
