Project name with full path (optional).
If not entered, the selected project is used when the action is called from GUI (like from a script or ribbon bar). 
If called from the windows command line, PROJECTNAME must be set or the 
must be used first, otherwise an  exception is thrown. 

Full file name of target file. Can't be null or empty.

Description which is contained in exported file. Value should be in multilang string format.