The IFilter interface scans documents for text and properties (also called attributes). It extracts chunks of text from these documents, filtering out embedded formatting and retaining information about the position of the text. It also extracts chunks of values, which are properties of an entire document or of well-defined parts of a document. IFilter provides the foundation for building higher-level applications such as document indexers and application-independent viewers. Full-text search engines like StopKa call the methods of this interface to extract text and property information for creating an index. Text viewers (like StopKa document panel) can also use this interface after a query, for example, to show the hit highlights for that file. On Microsoft site it is possible to find full interface description.