I am unable to understand the meaning behind the following extract from the ARP RFC 826:
For the 10Mbit Ethernet, the value in the protocol field (ar$pro) is taken from the set ether_type$. This is a natural reuse of the assigned protocol types. Combining this with the opcode (ar$op) would effectively halve the number of protocols that can be resolved under this protocol and would make a monitor/debugger more complex (see Network Monitoring and Debugging below). It is hoped that we will never see 32768 protocols, but Murphy made some laws which don't allow us to make this assumption.
How is this method restricting the protocols that can be resolved to half? The way i see it we can resolve 2^16 protocols using this method.