Aircraft Separation Over The Atlantic

[MightyGem]

What's the standard separation for aircraft over the Atlantic?

I was SLF to Boston last month and we were overtaken by another aircraft, and the separation looked to be about a half mile and 1000'. Not that I was concerned, it just looked closer than I expected.

[galaxy flyer]

Sounds perfect, 1,000 foot vertically. Before SLOP was consistently practiced, I crossed for nearly 30 minutes with a B767 within out wingspan, 1,000 feet above.

[BOAC]

Minimum subject to any errors will be 600'

Edited to add 'Instrument errors' in view of recent uncontrolled altitude 'excursions' covered on PPrune

[MightyGem]

Thanks for that.