The user manual’s introductory chapter still refers to old pnp4nagios. It says:
There is also a system for displaying graphs in the Checkmk Raw Edition. This is based on the Nagios add-on PNP4Nagios and is not interactive.
In the more detailed graphing chapter, the information is already up-to-date for 2.0, stating:
The interface for visualising the historical measured data is based on HTML5 and is identical in the Enterprise Editions and in the Raw Edition.