class E address

Hi everybody,

I have a question about class E IP address. I read a book which indicate that
class E IP address has the following format:
1111 xxxx . xxxx xxxx . xxxx xxxx . xxxx xxxx
Thus, the lowest address is 240.0.0.0 and the highest address is
255.255.255.254

Another document I read states that the format of class E IP address is:
1111 0xxx . xxxx xxxx . xxxx xxxx . xxxx xxxx

I try to verify in RFCs of IETF about this but I cannot. I read RFC 790, 791,
796 but they do not mention about it. Could you please give me the RFCs
indicating the format of class E?

In the first case I describe in this message, I wonder why the lowest address
of class E is not 240.0.0.1 because the adress with all 1 and all 0 have
special meanings (all 0 means "this" and all "1" means broadcast).

Thank you very much,
Mai Trang