Exclusion and inclusion filters are Ant file patterns that further define the set of source files to be considered by the Java builder and other JDT tools. To allow nesting of source folders inside each other, or simply to exclude parts of a source tree, one can associate exclusion filters to a source folder. Symmetrically inclusion filters can be used to inlude another part of a source tree. The Java builder will ignore source files that are excluded, and the ones that are not included.