Strange response from BRE <empty string>

As a
possible action from BRE I want to return an empty string, this is set as <empty
string> in BRE
Bur when I inspect the returned XML it will contain CR/LF (0D 0A) and two
spaces (20)
        
22 3E 0D 0A 20 20 3C
41                  
“>.. 
<A           

My problem is that in an expression
I would like to use “System.String.IsNullOrEmpt” but it fails, (of
course I could check for 0D 0A 20 20)