If a dataset is in research, in Dutch: "in onderzoek", it means the data owner is researching whether the indicated dataset can become available as open data. The results of the research are not yet clear, but in the context of transparency, the data owner can already indicate that the organization does have the data.
When a dataset is ready to be published as open data, the data owner can indicate this on data.overheid.nl. For data users it is interesting to know which data are on their way of becoming open data. If a dataset is marked with the status 'planned to be published', a date will also be specified. The data owner is obliged to indicate a date on which the dataset becomes available as an open dataset.