Keith Moore wrote:
The problem with a version number change is that existing clients won't know
how to handle a message with version != 1.0. So yes, you could change the
version number, but only if you're willing to completely abandon compatibility
with the installed base
[...]
To take an example from a slightly different field: IPv4 and IPv6
[...]
Same situation; IPv4 software has no way to deal with IPv6 packets. That hasn't
made all IPv4 software obsolete overnight, nor has it prevented IPv6 software
from being developed and deployed.
It's a matter of benefit vs. cost. In the case of the original subject, there
were a number of issues related to the overloading of compression (and
potentially
signing, encryption, etc.) onto Content-Transfer-Encoding in addition to
encoding, leading to a combinatorial explosion of potential CTE types, along
with problems for composing MUAs' attempting to automatically select an
appropriate CTE, potential DoS attacks, gateway issues, etc.