What is the 13th Period in Accounting?

I am seeing references to the 13th period in FundWriter. What is that, and what is it used for?

The 13th period allows you to enter adjustments without affecting a specific month in your organization's financial data. For example, at year end you discover that you need to adjust your Accounts Receivable balance, or make a minor adjustment to a cash account. You may not know the exact month that the account went out of balance, so the 13th period allows you to enter the adjustment and impact the year to date balance ONLY, without requiring that you adjust a specific month. The 13th period does not follow a chronological fiscal year...you can use any date you wish to enter transactions in the 13th period.

Setting up the 13th period adjustments does require assistance from DDI. If you are interested in utilizing the 13th month, please contact DDI Client Support.