[Serusers] avp, selects question

Hi all! I'm trying to learn more about the new function added to ser, for manipulating the information inside the script. One problem that I found was when I tried to use %var1= "value1; %var1 +="value2; What I was trying to do was to get a value from a header field %auth_hdr = @hf_value.authorization; and then %auth_hdr += "something"; is it possible? (I got an error) then I tried another way $auth_hdr = @hf_value.authorization; %auth_hdr_something = "%$auth_hdr, something..."; and worked. but what is the difference between using that or using instead of $auth_hdr, use %auth_hdr. Can I do this: %auth_hdr_something = "%%auth_hdr, something..."; tks in advance