The SectionFinder interface is used to implement the parser components which in the end create the Sections. You can look up the javadoc for details. However, in most cases it is not necessary to make a new implementation of this interface. There is already a zoo of different (partially generic) SectionFinders available. For the parsing of most simple markup the use of regular expressions is sufficient. Then an instance of the class RegexSectionFinder can be attached to the respective Type.