Unknown oil or water based stain - Pictures

Looks like a buildup of old stain as it has a slight sheen. This means it dried on top of the wood. Harder to remove and maintain.

I think it is Sikkens SRD or the Cetok DEK. Hard to say for sure.

Thank you. That's kind of what I was assuming. It's in pretty good shape really, no peeling or anything indicative of a solid colored stain. So likely the strip\brighten route best way to go? 

Strip off as much as possible, sand the rest of needed, brighten the wood when done. The current coating is thick so it will most likely need the sanding to remove fully.