[[MediaWiki:Globalblocking-logentry-whitelist/en]] and [[MediaWiki:Globalblocking-logentry-dewhitelist/en]]
@MarcoAurelio: Since you're a steward, do you have a way to try touching both logs (or, have you did some actions in the past that touch both?), so that we could know which "page" the $3 points?
I think $3 means the IP or CIDR being locally whitelisted or de-whitelisted.
I did some testing at <https://es.wikibooks.org/wiki/Especial:Registro/gblblock>. Indeed $3 seems to be User:<blockedIP/blockedrange> being whitelisted. I'll update the docs.