WGL_SAMPLES_ARB values of 0 and 1

When I’m calling wglGetPixelFormatAttribivARB to get WGL_SAMPLES_ARB value for some formats, I’m getting 0s or 1s (apart from getting 2, 4 and 8 for other formats).

Does anyone know what’s the difference between WGL_SAMPLES_ARB value of 0 vs 1? I imagine the both mean “No Anti-Aliasing”, right?