Electronic – Relay pins too close on PCB by design

If you have 50 of them, one easy way to figure the pins out would be to crack one open and have a look inside. The coil and connections should be clearly visible.

Another way is to use some Google-Fu and try the code or parts of it (you can add "relay" or "datasheet" to help narrow things down) and you may come up with something. I just had a go and I think this looks like your part's datasheet.

It should look something like the above if it is the right datasheet.
If you look closely you can see a similar format for rest of your code on the package example (the ARK-110 612 25W bit)

Since yours appears to the "single side stable version", this should be the pinout for it:

The resistor across the coil is a snubber, which will dissipate the extra energy and make sure the coil voltage never exceeds I*R, where I is the relay's "on" current.

Depending on R and I, you are completely safe, or you might see a controlled low-going transient at relay switch off. Notice high-going spikes won't be seen outside of the relay -- the series diode prevents it.

I wouldn't worry about it. You're not going to see the kind of uncontrolled spike that you get when a bare coil is looking for a place to dump its energy.