Adding Functionality to Your Cube - Getting Started with SQL Server 2012 Cube Development - page 172

A calculation can also reference another calculation; however, when you define such
a calculation, you have to understand that the order of where they are defined
in the script matters. More information about Solve Order can be found at ht-
tp://msdn.microsoft.com/en-us/library/ms145539.aspx .
Time and date calculations
The most common type of calculation when doing analysis is time calculations. It is
always necessary to review sales by comparing how sales performed this year com-
pared to the previous year. There are several ways you can perform time and date
calculations, one is to use functions such as Lag and Lead that navigates in the di-
mensions giving the members before and after the current member. Another one is
to use the time calculations such as ParallelPeriod and YTD (short for year to
date).