question on a SPF setting

[Wesley Peng]

Hello

I saw myrambler.ru has a special setting for SPF:
myrambler.ru.           3599    IN      TXT     "v=spf1 
ip4:81.19.78.96/27 ip4:81.19.78.0/27 ip4:81.19.88.0/24 
-exists:%{ir}.spf.rambler.ru ~all"

what does it mean for this part:

-exists:%{ir}.spf.rambler.ru

Thank you.