External IP address pattern

1. Brekeke Product Name and Version:

Vers 3.1.7

Just a quick question, under the config settings what is the
"External IP address pattern" field for and how it's used, can't find anything about it in the manual or the wiki.

http://www.brekeke-sip.com/download/bss ... min_en.pdf

It said:
External IP address pattern
Regular-expression based IP address pattern which should be treated as an external IP address.

Thanks for that.
Oddly it's not in the V3 document, hence I didn't pick it up.