Except

Set operation, which returns members of Set1 but removes any members that are in Set2.

Syntax

Except(Set1_Expression, Set2_Expression)

Arguments

Set1_Expression	MDX expression that returns a set of members that should be included in the final set.
Set2_Expression	MDX expression that returns a set of members that should be excluded from the first set in the final set.

Examples

The following formula will aggregate all priorities and not include High and Highest members

Aggregate(
  Except(
    [Priority].[Priority].Members,
    {[Priority].[Highest],
     [Priority].[High]}
  )
)

See the example report Issues created high vs low priority this and previous year in our demo account. The calculated member Medium and Low in dimension Priority uses the formula above.

When defining the Set_Expression_1 (the set from which to take out elements), ensure to define the member level to avoid including the dimension default (All level) member. Otherwise, all excluded members would still be included in the calculated member as a part of All level members.

CORRECT

Aggregate(
  Except(
    -- addresses members of a particular level only
    [Priority].[Priority].Members, 
    {[Priority].[Highest],
     [Priority].[High]}
  )
)

INCORRECT