see [[Query|Query]].
==FilterClass==
The FilterCLass is a reference to the root node where all the matching content is beeing compared to with the query criteria. The root node itself does not need to fullfill the classification [[SYSCLS_OBJECTWITHIDMARKER]] as all derived MetaClasses are recursively checked for implementing the classification interface. All the found matching content then is aggregated to one query result.
{{Attention|When selecting the query root node, please consider that possibly a huge amount of derived MetaClasses must be recusively checked for implementing the classification interface! Using a FilterClass that directly implements the interface reduces the processing time to a minimum!}}