[Boost-users] Boost spirit... classic?

Hi, I'm a bit confused. It seems like all the includes for boost spirit are "classic" i.e. it seems to me I have an old version, but I'm currently using 1.39. I looked on the spirit website and there is no information about the correct way to use the latest version of the spirit framework. The most I found was a post from about a year ago about the "classic" includes. The documentation on the boost website doesn't have any information. Is there some information about this somewhere? What should I be doing to create new parsers? Kind regards, Samuel