Advanced tab gets a mini forwarder to choose where pack updates come from. The channel is stored as release_channel in /config/omninx/manifest.ini; master builds ship it set to master. Master downloads OmniNX-<Variant>.zip and RELEASE.ini from the 'master' release in OmniNX/OmniNX-Master, release keeps using the latest non-prerelease of OmniNX/OmniNX.