Below basic InterForm400 package and the modules are described.
As minimum you need to buy either the InterForm400 Light version or the basic InterForm400 package.
If wanted you need to install the additional modules InterWord400 and InterFax400. InterFax400 is installed via option 80 on the InterForm400 Service menu and requires the InterForm400 CD. The other modules are installed along with InterForm400 and only need to be enabled with a new license code.
Refer to here for details of the light version.