Filters have a number of uses in OBO-Edit at the moment, and others will be added in the future.
The use of filters to control editor displays is described in the Filtering document.
Currently, filters can also be used to restrict which terms and links are written to an OBO file. By specifying different filters for different files, it is possible to split an obo ontology into several different files. See The OBO Adapter for more information.
In the future, filters may be used to do automatic subset assignment, modify the appearance of the GraphViz Plugin, or apply a similar edit to several terms.