Filter definitions let you filter the data for your report. BUT there are two completely differnet type of filters, that have a different purpose:
Select filters are filters, that are displaied when generating a report, to select specific objects you want to put on your report.
Select filter types are:
Select filters are shown in the filter selection when generating the report.
For a filter definition you have a lot of options available. Here only the most important options will be explained
Only select filters you can make dependent on other select filters.
Hidden filters do not show up in the filter selection when generating the report. So hidden filters have NO EFFECT on select filters even if you make select filters dependend on hidden filters!