A relative period reference specifies the number and/or type of periods to lag or lead:
A lead references time periods following the current time period.
A lag references time periods prior to the current time period.
For each reference, you must indicate whether the time periods are a lag or a lead:
If you specify no period type, the type becomes the same as the current period. For example, if you are in a month then you lag by months, or if you are in a year then you lag by years.
You can retrieve an account value from a nonexistent period. For example, if you forecast January 2003 Sales based on growth rate from the previous year (January 2002 Results), but 2002 is an annual period, Strategic Finance interpolates the answer based on the final Result for 2002. This will not predict variance.
See Functions that Typecast Within Relative Time Period References.