Agreed.

BMW's have a very similar power steering architecture. Probably sourced from the same subsystem supplier. My 2 BMWs use CHF (green). But earlier years used ATF (red). My XK uses Dextron 3 (redish), an ATF.

My 2 cents: look at the color and replace with what's in there. Dex 3 is pretty distinctive, so it should be obvious what's installed. Does it matter if we mix them? Who knows? Just don't do bother to do it, and we never have to find out.

Also, I recommend we change out the reservoir and it's resident filter at some point after 80+K mi. I replaced mine while doing a maintenance manual full flush. The old fluid was cloudy, and the fluid flow through the reservoir was dramatically improved in the new reservoir with a new filter. Replacing the reservoir is a very easy job. YMMV, etc.