This module allows to reverse several elements such as invoices, vouchers and account entries in Odoo.
A reversal can be from that certain products or accounting charges recorded during a year does not concern only one. For example, a one-year subscription to a magazine subscribed September 1 must be distributed at 4 months ( 1/3) of the current fiscal year and 8 months (2/3) the following year. 2/3 of the registered charge will therefore be " reversed " the following year.
You can find a related post for the exemple at: http://bit.ly/1C7pWNB