I saw this series of 4 circles in the schematic of an Arduino board. Similar circles appear in other Arduino schematics, though I don't think they are Arduino specific (which is why I post here rather than on the Arduino forum).
What do they mean?
Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up.Sign up to join this community
OK, I found an Eagle schematic file of this, and I checked the properties, like jwsc suggested. They seem to represent fiducials.
Comment: fiducials don't belong on a schematic, they're purely PCB-related. You don't place mounting holes on a schematic either. When they appear on a schematic they will most likely show up in the BOM as well.