OP5 Monitor is using PNP to create the graphs available for most standard services in the user interface.
PNP is an add-on to nagios which analyzes performance data provided by plugins and stores them automatically into RRD-databases (Round Robin Databases).
PNP only processes performance data built according to the Developer Guidelines for monitoring plugins. With this limitation we want to honour the work of Nagios Plugin Developers who stick to the guidelines. This is a short description of how to use PNP and it's functions pages and templates.
For more info please refer to the online manual for PNP.
Kudos to Joerg Linge for letting us use his text.