.jpg files is set as C:\Viewer.exe then the program C:\Viewer.exe will be launched when you open the file Image.jpg in Windows explorer. By selecting the Open With / Registered Association command in PMIO, you make sure that the image is opened in your preferred application for that file type. These associations are set in Windows explorer by choosing the View / Options command and selecting the File Types tab.Note: To make Registered Association the default PMIO viewer, move it to the top of the application list. For more information on how to do this, see Preferences.