The CurrentMember function
The CurrentMember function is the most important function in MDX, understanding how it works is the key to being able to write all kinds of really useful calculations in MDX, including time intelligence calculations.
What it does is this? when you call it from inside a calculation, it tells you where the calculation is being executed inside the space of the cube. In other words a calculation is executed inside a cell, and a cell has a tuple that points to it, the CurrentMember function allows you to inspect that tuple, and to ﬁnd which member from any hierarchy on any dimension in the cube is present in that tuple.
The CurrentMember function can only be used with a hierarchy object, and it returns a member object. Using this function is essential while building calculations which include related metrics, such as sales values from diﬀerent time periods.
In most real-world calculations, you use the CurrentMember function to construct tuple or set expressions to ﬁnd values elsewhere in the cube, relative to the cell you are currently in.
Read more MDX Calculations Part 2 – CurrentMember Function