I learn new things about IPv4 every day. Over the weekend there was an article about someone writing an IPv4 address parser and there were a couple of cases th

I learn new things about IPv4 every day. Over the weekend there was an article about someone writing an IPv4 address parser and there were a couple of cases that were new to me. One thing about "second system syndrome" that doesn't get talked about much is how the second system always has to take into account the unwritten rules from the first system, that the original designer didn't take into account. What was previously unspecified now becomes specified, and that increases the amount of text in the second system's specification. But, the complexity might not be as high -- it's just that you can read about it all in one place.