In my special case I have to create several custom exclusion for the antivirus engine of SEP Small Business Edition Cloud. This exculsions refer to the users-folder of Windows. Therefore I wanted to use C:\Users\%USERNAME%\...\... but I learned that this does not work. So I have to use:
C:\Users\Username1\...\...
C:\Users\Username2\...\...
C:\Users\Username3\...\...
C:\Users\Username4\...\...
...
Not that practical. Please add the feature to use Windows environment variables for custom exclusions