Without more context, this is just a guess: is the logo itself dark and has a white background? In that case the positive (like on a slide, e.g.) would indeed be as described, and if it's a negative (either a b/w or color negative), it would be the opposite.

Yep, dude, you're spot on. The logo is indeed black/grey with a white background. So therefore "Positive on white or taupe. Negative on black." sounds ok?

Sounds okay to me

Many thanks, dude :-)