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   RE: [xml-dev] Xml is _not_ self describing

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I can't wait to see the XML.COM condensed 
version of this thread. :-)

Is it there?  We can split some fine hairs here, but 
often meaning has to be discovered from clues found 
elsewhere and then projected onto the text.  Worse, 
the translations into an understanding readily shared 
can vary enormously such that any such original meaning 
is distorted or not provable as original until some 
acceptable number of texts are translated.  There are 
linear markings from the Mystery Hill site (American 
Stonehenge) which some claim are Phoenician but are 
hotly contested otherwise.  Before accepted, both 
the decipherers and the archaeologists have to 
find mutually reinforcing but quite separate 
evidence (previous examples of the text types and 
artifacts attributable to some past civilization). 

It may not be random but be meaningless:  see the 
problems of assuming some astronomical signals 
were meaningful because they were regular (rotating 
and emitting).  Non-randomness isn't meaningful 
per se.  One can assume that a wedge-shaped tablet 
found in a collection of such is if other evidence 
indicates the site is a library, then start building 
up example sets until the key is discovered or a 
dictionary is created that self-consistent to a 
tolerable degree.  Otherwise, a Rosetta Stone is 

So it isn't that cut and dry.  As I said in my 
reply to Mike, you can be looking for math only 
to discover belatedly, possibly by accident, that 
they were just saying Hi: Cheops Slept Here.  Once 
you know about star alignments, some aspects of 
pyramid layouts make sense.  Unfortunately, 
so does Stonehenge, Mystery Hill and a myriad 
of other sites - but it can't be proved and 
may not be true in each or every case.

"Documents written in natural languages have meaning even if you don't 
speak those languages. They do carry information."

That is so but until you learn them or someone who has tells you, 
you don't know what they mean.  We are quite close to the 
"if the tree falls in the forest.." argument.  The best I can 
do is say, yes it has meaning to someone and yes, strictly 
speaking, by establishing the non-randomness is purposeful, not 
a side effect of another regular process, we can agree there 
is information there.  Shannon built modern communications 
by saying reproducibility, not semantics, are the key to 
designing communication systems.

That said, we of course agree about the value of tagging regardless 
of whether we have the descriptions.  XML is self-describing to 
the extent one understands the Rosetta Stone that is the 
XML 1.0 specification, then acquires by some evidence, a 
workable set of descriptions for the tag names.  Doctor Goldfarb 
often points to glossing as the original modern form of hypertext
and markup.

All other things being equal, given some XML instance, I sure 
do prefer a well-documented schema or DTD to reading someone 
else's code to discover what I am supposed to expect and 
what to do about it.  Or just Hide The XML and give me 
the stinkin' compiled application to install.


-----Original Message-----
From: Elliotte Rusty Harold [mailto:elharo@metalab.unc.edu]

At 12:17 PM -0600 1/15/02, Bullard, Claude L (Len) wrote:

>A label is not a name unless it is meaningful.
>Natural language is not self-describing unless
>you were taught it.

I guess it depends on what exactly you mean by "self-describing". I 
think a book about the English language written in English is 
self-describing in and of itself, whether anybody speaks English or 
not. However, leaving that aside there's a deeper assumption I want 
to cut off before it becomes too embedded in the debate.

Documents written in natural languages have meaning even if you don't 
speak those languages. They do carry information. They are not random 
strings of characters. I've been reading a lot about the theory and 
history of cryptography  lately, and it's amazing just how much 
information you can pull out of ciphered text, because, in fact it 
isn't random. It's harder to read ciphered text than unciphered text, 
but it's not impossible. And that's a world of difference.

Reading text in a language you don't speak, but which has not been 
deliberately encrypted, is a similar problem; and in fact some of the 
same techniques were applied to languages like Linear B and 
hieroglyphics that are used to break ciphers.

When a document is marked up, the information of the markup is there, 
whether we recognize it or not. It is a property of the text itself, 
not a property of our perception of the text. With appropriate work, 
experience, intelligence, and luck that markup can be understood. Can 
unmarked up text be understood as well? Yes, certainly; but markup 
adds to the information content of the text. It makes it easier to 
decipher its meaning in a very practically useful way. This is a 
question of degree, and text+markup is easier to understand than text 

Langauge is certainly important, but it is orthogonal issue.  Given 
the choice of data marked up in Ugaritic vs. the same data marked up 
in English, I pick English. But given the choice of data marked up in 
Ugaritic vs. the same data not marked up at all, I pick the data 
marked up in Ugaritic.


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