It looks like this is used to split databases,
This will backup all Accounting Master and Transactions starting from the specified date.
Great feature, and much needed for businesses with large transaction data.
I suspect this is an unannounced precursor to the ability to separate and possibly purge older transactions, rather than let them accumulate forever. The developer has mentioned such a potential feature.
It would not be the first time a feature has been quietly added without notice.