3.4 FDT Type Library

COM type libraries can only use a two-part version number. If only the minor version number increases, all the features of the previous type library must be supported in a compatible way. If the major version number changes, code that compiled against the type library must be recompiled. The version number of the type library may differ from the version number of the application.

The four-part FDT version number is mapped to the two-part type library version using a COM minor version consisting of 5 digits. The first digit represents the FDT minor version, the second and third the FDT release version and the fourth and fifth digit represent the FDT build number (e.g., FDT 1.2.0.1 is represented as type library version 1.20001, FDT version 1.2.1.0 as type library version 1.20100).

According to COM rules a new FDT COM type library will be downward compatible to a previous version of the same major FDT version.

The FDT version (major, minor, release and build) is used also as version number of the fdt100.dll file. This assures that a new version replaces an older version during installation.