It's lasered on.
Upon a closer inspection, I think you're right... laser which cut right through the blue. A nice place for rust to start eventually. Thanks UN! You surely make a difference in de-valuating legit firearms (but that's pretty much all you do with this horsesh*t).
I'll try some cold blue on it and see if it helps. Besides, I don't think we (or anyone for that matter) should consider UN authority seriously. They're totally anti-democratic (we as the people have no say in their decisions) and that goes against our very principles.

Edit: ok, just tried it... here's the result. Sorry about the poor pic quality, but my good camera is currently unavailable.
Before:

After reblue (you can see the kit next to the Tok). Markings still visible, but a LOT less:

Note: To do it properly, one would have to strip the blueing completely off the slide (or at least off a larger section of it) and reblue with a professionnal product. The blueing kit you see pictured is only good for minor touch-ups and tends to rub off with time (temp solution only). I know our friends down south have some very good stuff called 'oxphoblue' (or something similar) that yields a very professional result. I was looking for it all over the place years ago, but it turned out that it's not available up here.. as it's usually the case.
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