[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message]

Re: Case sensitivity

  • From: Steve DeRose <Steven_DeRose@b...>
  • To: xml-dev@l...
  • Date: Mon, 3 Apr 2000 12:44:37 -0400

is xml case sensitive
At 10:27 AM -0400 4/3/00, Eric Bohlman wrote:
>On Mon, 3 Apr 2000, Stefan van den Oord wrote:
>
>> I have a simple question, I think: is XML case sensitive? In other words,
>> are the tags case sensitive? I also mean the <?XML... tag and the <!DOCTYPE
>> tag.
>
>Yes, XML names are case-sensitive (remember that they're not restricted to
>being English names, and many non-Western languages don't even have a
>concept of case-folding).

Your answer is of course correct (XML is case-sensitive); it is also true
that "many non-Western languages don't even have a concept of
case-folding". However, the second is not the reason for the first
(granted, you didn't actually say it is -- but a reader might well take it
that way).

Languages with no need for case folding are not much of  a problem: the
case-folding table or program would merely have no effect on characters
belonging to such languages: It would change 26 of our 26 alphabetic code
points, and no others. After all, in English we already use lots of
characters that don't get case-folded (like digits).

The serious problems are subtler:

The practical problem that with Unicode your folding table gets really big;
on the order of 128Kbytes instead of 256 bytes (barring compresson): this
is a pain on small devices (like a cell-phone browser), a pain to load, a
pain to implement compression for, etc.

The theoretical problem is more important: it's not the caseless languages
that pose problems, but the complicated case-folding ones. For example,
lots of languages only apply diacritical marks to lower-case letters: for
example, "a" may come with 6 different accents, but "A" takes none -- which
makes case-folding unreversible. If there are languages that operate the
other way as well, then neither fold-to-upper nor fold-to-lower can work
for all languages: either way would trash some languages.


That said, I think it incumbent on XML *search engines* to support
case-folding (as well as decent treatment of accents, types of hyphens,
etc) for text content searches: Making English speakers search for

  "the" | "thE" | "tHe" | "tHE" | "The" | "ThE" | "THe" | "THE"
or
  "[tT][hH][eE]

is patently absurd; and besides, there is no user cost to (say) a Japanese
speaker if an engine *does* case-fold. Also, many languages use Roman
characters occasionally, as for acronyms; so their speakers also pay a
price if searches aren't smart enough. And the primary problems with
case-folding do not weigh so heavily in the search engine world (for
example, AltaVista isn't likely to run their main servers on cell phones
for a while yet).

Steven_DeRose@B...; http://www.stg.brown.edu/~sjd
Chief Scientist, Scholarly Technology Group, and
   Adjunct Associate Professor, Brown University
North American Editor, the Text Encoding Initiative



***************************************************************************
This is xml-dev, the mailing list for XML developers.
To unsubscribe, mailto:majordomo@x...&BODY=unsubscribe%20xml-dev
List archives are available at http://xml.org/archives/xml-dev/
***************************************************************************

PURCHASE STYLUS STUDIO ONLINE TODAY!

Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced!

Buy Stylus Studio Now

Download The World's Best XML IDE!

Accelerate XML development with our award-winning XML IDE - Download a free trial today!

Don't miss another message! Subscribe to this list today.
Email
First Name
Last Name
Company
Subscribe in XML format
RSS 2.0
Atom 0.3
 

Stylus Studio has published XML-DEV in RSS and ATOM formats, enabling users to easily subcribe to the list from their preferred news reader application.


Stylus Studio Sponsored Links are added links designed to provide related and additional information to the visitors of this website. they were not included by the author in the initial post. To view the content without the Sponsor Links please click here.

Site Map | Privacy Policy | Terms of Use | Trademarks
Free Stylus Studio XML Training:
W3C Member
Stylus Studio® and DataDirect XQuery ™are products from DataDirect Technologies, is a registered trademark of Progress Software Corporation, in the U.S. and other countries. © 2004-2013 All Rights Reserved.