Understanding Locked Windows (6376)
There are times when you can't enter or change information in a window that you open. When you can't make changes to a window, it is considered locked. When a window is locked, a small lock icon appears in the upper-right corner, near the path icon.
There are two ways windows can be locked:
When the Big Business administrator protects information within certain periods to prevent unauthorized changes. In this case, the date of the window is displayed in red to tell you that it falls within a protected period. See "Setting Maintenance Preferences" in Chapter 12 for details about protecting data.
When it is inappropriate to make changes. For example, once you have made a payment against a bill, you can no longer make changes to the bill.