It's been 20 years today (Oct 16, UTC). Hard to believe.

Wayne Bouchard web at
Tue Oct 16 23:57:31 UTC 2018

Well, simply put, the idea is that you should be able to compensate
for a certain amount of deviation from accepted usage as long as its
still within what the protocol allows (or can be read to allow) but
that you yourself should act with a fairly strict interpretation. In
others, don't be the one *causing* the problems...

On Tue, Oct 16, 2018 at 11:10:31AM -0700, Brian Kantor wrote:
> On Tue, Oct 16, 2018 at 02:01:48PM -0400, Daniel Corbe wrote:
> > The one thing I remember about Postel, other than the fact that he had his  
> > fingers in a lot of DNS pies, is be liberal about what you accept, be  
> > conservative about what you send.  It???s a notion that creates undo burden  
> > on the implementor, because it places the expectation on the that you need  
> > to account for every conceivable ambiguous corner case and that???s not  
> > always the best approach when implementing a standard; and it mostly arises  
> > from the lack of adherence to the second part of that statement.
> I think that his aphorism is simply a recognition that NO standard
> can cover all cases that might arise when dealing with complex
> matters, no matter how much thought went into it.  People are
> fallible, and the standards they write are inevitably flawed in
> some way, so a realistic implementor has to allow some slack or be
> continually engaged in finger-pointing when something doesn't work.
> 	- Brian

Wayne Bouchard
web at
Network Dude

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