ThinApp User’s Guide : Configuring Package Parameters : Configuring File and Protocol Associations : FileTypes

The FileTypes parameter lists file extensions that the thinreg.exe utility associates with an executable file.
The capture process generates initial values that you cannot add to. You can remove extensions that you do not want to associate with the virtual package. Do not use separators between the file extensions in the list.
A Microsoft Word 2007 package specifies .doc.docx as the values of the FileTypes parameter. If you capture Microsoft Office 2007 and have Microsoft Office 2003 installed in the physical environment, you can remove the .doc extension from the FileTypes parameter and leave the.docx extension to ensure that Microsoft Word 2003 opens .doc files and Microsoft Word 2007 opens .docx files.
[Microsoft Office Word 2007.exe]
The capture process can create file type associations for .doc and .dot extensions and link them to Microsoft Word.
[Microsoft Office Word 2003.exe]
Source=%ProgramFilesDir%\Microsoft Office\OFFICE11\WINWORD.EXE