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Re: Display types?
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At 07:10 PM 3/15/99 +0000, Paul Crowley wrote:
>Ron Rivest <firstname.lastname@example.org> writes:
>> I agree with you both the display types are a debatable feature of
>> SPKI/SDSI. They obviously add a little bit of complexity. On the
>> other hand, they have the following benefits:
>> (1) they allow the use of names over a non-Latin alphabet
>> (2) they allow incorporation of pictures and other document
>I think these advantages are both important features of SPKI/SDSI, but
>as far as I can tell they can be done without the complexity of
>display types, by adding an entry in the BNF definition for typed data
><printable>: <byte-string> | <mime>
><mime>: "(" "mime" <mime-type> <mime-data> ")"
>or something like this.
If MIME-typed byte strings were always to occur in parameters, this might be
a valid solution, but as I recall the original debate on this topic, we were
concerned about letting people use their native character sets for type
names of sub-expressions (the initial bytestring in an expression).
If we were to go to UTF-8, then that removes the need for MIME types for the
S-expression type name. We would allow <printable> only as parameters
in S-expressions, not as type strings. This allows us to retain the
constraint that the first element of an S-expression is a bytestring.
We started out with UTF-8 as the character set and the discussion on the
list pushed us back to Latin-1. I believe the primary objections were from
If we were to assume UTF-8 for a character set, we also have the problem
that it's a variable width character set, which means that the byte count
that preceeds a bytestring would not always equal the character count. This
would have little effect on a program but might get in the way of a human
examining the canonical form from a text display.
What is the sense of the group here?
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|Carl M. Ellison email@example.com http://www.pobox.com/~cme |
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+--Officer, officer, arrest that man. He's whistling a dirty song.-+