library for dealing with Microsoft CHM files It is a very simple library, but sufficient for dealing with all of the chm files. Library currently does not has write support. CHM files are used on the Microsoft Windows platform to store program documentation, almost always in the form of HTML, with some non-standard quirks. CHM files are a form of archive known as InfoTech Storage Format (ITSF) files and contain some special files to implement features of the CHM viewer.