Balance Sheet periods in Financial Report Designer (8.03.409c)

Does anyone know what(or how) the Number of Periods value in a report Column affects a Balance Sheet report? Changing it, yields different report outputs.

We initially set it to equal the number of periods in the fiscal year. But we need to "extend" this FY from 12 to 15 periods, as we are trying to sync up the fiscal and calendar years.

I'm no CPA, but isn't a Balance Sheet(B/S) report for a single instant in time? Where as the Income Statements(I/S) are for one or more periods (YTD, last month, last 3 months, 1st Quarter, etc...)?

So having a "Number of Periods" field for an I/S makes sense. But there doesn't seem to be the need for it on a B/S report.