The order of CustomLinks is loosely based on SFX sort_services.config ranking. Here is the basic order, with space for tweaking.

10 = Paid publisher subscriptions 20 = Publisher hosts (there weren’t any) 30 = Newspapers 40 = Databases 45 = Media, image, and streaming 50 = Less reliable aggregators and digitized historical publications 60 = eBooks 70 = Open access 80 = Reviews