A question about the str( ) function on IRI

Hi,
I believe this is a trivial question, but it did confuse me for a long 
time.  In the Section 11.4 "Operators Definitions", the description for 
str() says "returns the codepoint representation of rsrc (an IRI).".  I 
think the "codepoint" means the code of characters, in non-negative 
integers.  So I wonder why the "codepoint" is used here.  Also, I think 
some of the readers (include me) may think if the result of 
str(<mailto:alice@work.example>) is "<mailto:alice@work.example>", but not 
"mailto:alice@work.example".  Unfortunately, the following example uses a 
regex function to test the value, so that it can not be used to distinguish 
the above two possibilities. (Although I believe that the answer should be 
"mailto:alice@work.example")