Processing Options in the Custom Actions

1. Synchronous:
 Windows Installer runs the custom action synchronously to the main installation. It waits for the custom   action to complete successfully before continuing the main installation.


2. Synchronous, ignore exit code 


Windows Installer runs the custom action synchronously to the main installation. It waits for the custom action to complete before continuing the main installation; the action can be either success or fail.


 3. Asynch, wait at end of sequence 


Windows Installer runs the custom action simultaneously with the main installation. At the end it waits for the exit code from the custom action before continuing.


 4. Asynch, no wait 


Windows Installer runs the custom action simultaneously with the main installation. It doesn’t wait for completion of the custom action and doesn’t check the exit code also.