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

Re: terra incognita

terra terminal
At 6:53 PM +1100 12/19/01, Alan Kent wrote:

>Is there a good reason why PCDATA should not be allowed to contain the
>bell (BEL) or escape (ESC) character? Why is it always evil to allow
>terminal escape sequences to be embedded in an XML document? Why is it
>important for XML to *not* permit it to be used for things that it was
>not originally intended for?

Among other reasons, because these characters can have unexpected 
consequences when presented on dumb terminals and terminal emulators, 
passed through gateways  and routers, and in other systems. None of 
the kinds of things that have these problems are very common today, 
but they're out there; and they are used. (I just used a terminal 
emulator to check the version of emacs for a different thread.)

>Hmmm. I must admit I just confused myself. Looking at the Unicode 3.0
>book we have, it defines C0 controls (0x00-0x1f) and C1 controls
>(0x80-0x9f). The XML 1.0 spec says it allows "any Unicode character
>excluding the surrogate bocks, FFFE, and FFFF". It then lists #x9, #xA,
>#xD, #x20-#xD7FF etc. So why are *some* C0 control Unicode chars
>"not Unicode", but *all* C1 control Unicode chars "are Unicode"?
>It seems totally self-contradictory and bizare to me.

It is, and this is an admitted mistake in XML 1.0. The C1 controls 
should have been banned like the C0 controls. It was an oversight 
that they weren't.

| Elliotte Rusty Harold | elharo@m... | Writer/Programmer |
|          The XML Bible, 2nd Edition (Hungry Minds, 2001)           |
|              http://www.ibiblio.org/xml/books/bible2/              |
|   http://www.amazon.com/exec/obidos/ISBN=0764547607/cafeaulaitA/   |
|  Read Cafe au Lait for Java News:  http://www.cafeaulait.org/      |
|  Read Cafe con Leche for XML News: http://www.ibiblio.org/xml/     |


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.
First Name
Last Name
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.