Source Insight records each source file's signature in the project database. The signature is composed of the file’s modification date, plus the file’s size. If you open a source file later and the file's signature differs from what is in the project database, then Source Insight will re-synchronize the project symbol database for that file. By automatically synchronizing, you or others in your development team can use another text editor or a source control system and still maintain Source Insight's project databases. See: Synchronize Files.