1. Given how easy it is to detect the zero bytevector and the zero
string, the SRFI should be required to signal an error. I don't think
there are any extension opportunities there either.

2. I think it would be good to specify what it means to position a
cyclic port.

3. SRFI 271 (which is still in draft) should reference this SRFI to
comment on ways to initialize ports.

-- Peter McGoron