My ancestor Charles Olive had a son born in Java, Indonesia in 1843, and the records show "en van Chinese vrouw Ong Tok. (erkenning.) Vrouw means woman or wife, and erkenning means "recognised", so I am assuming this was his first wife, but was she actually married to him, or just recognised as an accepted common law wife, or something else?

I don't think they where married.
But ask the question on the Netherlands General Board.
You get more response there.

I found entries of a Charles Chappel OLIVE in the Regeerings Almanak. Erkenning means recognised, but it doesn't refer to the Chinese woman, but to the son. Charles recognised the son as his child. He wasn't married to this Chinese woman.
Hope this helps.

Many thanks for your reply. I am very grateful. Mike.