You can have any position you please. The handlebars are continuous variable from Omafiets, the real ‘dutch’ posture, to a modern posture, with the handlebars at 45 degrees, to very sportive, this is the same position you would have on a mountainbike. The handlebars always pivot symetrical due to a little mechanism. The position of the handlebars is firmly locked with a eccentric handle taking out any play.
The sit up and beg position is great for in the city, you sit higher and the neck is free to rotate so you are well aware of the traffic around you, but for a bit of speed, the position sucks, too much wind resistance and no good in putting force on the pedals.
An additional idea was to use the handlebars as a lock, more about that here