The principle investigator (PI) is the person beeing responsible for the scientific quality of a data series. PI has a 1:1 relationship to data series which means that just one PI can be related to one data series. In case more PI want to be related to a data series, the names may be added in the data series comment field (this should be an exception!). A PI must be defined in the staff list to be related to the data series during the import procedure. A data set may have as many PI as data series (but may have as many authors as required).