Freeze
Clicking Freeze causes all freezable bill segments to become frozen. Refer to Bill Segment Lifecycle for more information about freezing.
This button is enabled if:
• the Freeze At Will Bill Segment Freeze Option on the installation option has been selected AND
• freezable bill segments exist AND
• there are no error, incomplete or pending cancel bill segments.
Note: 
Freezing a day or more after generation. If, during freezing, bill segments in closed accounting periods are detected, a pop-up appears in which you can specify a new accounting date; this date is updated onto the offending bill segments. This only happens if the accounting period closes before you freeze the bill segments (the accounting date is stamped on a bill segment when it's generated).
If, after freezing, you're ready to send the bill to the customer click Complete to finalize the bill.
Note: 
If problems are detected after freezing. A bill segment may not be changed after it is frozen. All subsequent changes must occur by canceling the frozen bill segment and creating a new bill segment. Refer to How To Cancel A Bill Segment and How To Cancel / Rebill A Bill Segment for more information.