SmartPlant Foundation uses the "Conversion required for navigation" property to determine if a file of a given file type should be converted using the SmartConverter when it is viewed with the View and Markup command. By default, this property is turned off, which means no files of this type will be converted. You can change this condition by running the Update command on any file type.
The Convert for Navigation command can be used to SmartConvert any file regardless of the "Conversion required for navigation" setting of its file type.