How to find and differentiate Documents number in next financial year

Hi Everyone,
However, I have never checked that, but I just wanted to know when the financial year changes from 2015 to 2016.
What will be the new document numbers? Will they again start from one? If yes then how will we differentiate that the number belongs to 2015 or 2016 and if no, then what is the way to give new numbers from the start to the documents created in 2016.

Regards
Ruchin Sharma

You can add a prefix like INV-15-.#### etc. See: https://frappe.github.io/erpnext/user/manual/en/setting-up/settings/naming-series.html