If you want to manage the Brazil compliance with SNM (a randomized 13 digits serial number), you have to:
1- set the serial number not unique accros all products in order to manipulate several product codes.
2- create a range with 10 digits serial number length starting (beginIndex) from 1000000000
3- assign as many GTIN as needed to that Brazil range: it will manage the serial number uniqueness across all assigned GTINs.
4- When allocating serial number, use the randomization feature in order to add 3 extra digits to the generated serial numbers.
5- as output format, you can use either epcUri or human readable.

Note:
You can also, later on, add more product codes to that range. For that you will have to change the end index and revert it in order to enable the OK button. This is a protection against unintentional changes.