[^^:sip_invite_domain=example.com:presence_id=1010@example.com]sofia/external/sip:1010@192.168.56.1:59527;ob;fs_nat=yes;fs_path=sip%3A1010%40192.168.56.1%3A59527%3Bob

Are there any decent resources that would help me understand this better? 

As I understand it the [...] at the beginning means, apply variables to the channel, but what does the ^^ mean?

And what does the bit after the address do/mean? i.e. in this specific case the bit

;ob;fs_nat=yes;fs_path=sip%3A1010%40192.168.56.1%3A59527%3Bob

Thanks

Mark