On 14 Nov 2005, at 6:11 PM, Daniel A. Nagy wrote:
But how to express "you should print this"? I tought the text flag
critical flag together were for this very purpose.
The critical flag can called (only slightly humorously) the non-
Normally, when an implementation sees any subpacket it doesn't
understand, it ignores it. But with the critical flag, you error out
if you don't understand it.
So ihf you create a human-readable, critical notation, you're asking
for it to blow up a lot. This may be exactly what you want, but it
Now this can create side issues, as well. Let's suppose that I have
built an automated system (one with no humans). I know exactly what
your notation is, but I have no human. So I ignore the thing. To me,
this follows exactly the spirit of "critical" because I know what it
is and I know I can ignore it. It may not be what you want -- you may
have thought that human-reable and critical means it will blow up any
Similarly, I might display the notation to a human user and have a
"please don't show this to me again" check box to have it not
displayed again. This is a reasonable thing to do, despite a critical
This is why I put my tongue in my cheek a bit and call it also the
non-interoperable flag. If you set the critical flag, you create all
sorts of interesting ways for the system to surprise people.