Datasheet

Chapter 1 ✦ An Eagle’s Eye View of XML

XLinks are discussed in Chapter 17.

XPointers allow links to point not just to a particular document at a particular loca-

tion, but to a particular part of a particular document. An XPointer can refer to a

particular element of a document; to the first, the second, or the seventeenth such

element; to the first element that’s a child of a given element; and so on. XPointers

provide extremely powerful connections between documents that do not require

the targeted document to contain additional markup just so its individual pieces

can be linked to another document.

Furthermore, unlike HTML anchors, XPointers don’t just refer to a point in a docu-

ment. They can point to ranges or spans. For example, an XPointer might be used

to select a particular part of a document so that it can be copied or loaded into a

program.

XPointers are discussed in Chapter 18.

Unicode

The Web is international, yet a disproportionate amount of the text you’ll find on

it is in English. XML is helping to change that. XML provides full support for the

Unicode character set. This character set supports almost every character that is

commonly used in every modern script on Earth.

Unfortunately, XML and Unicode alone are not enough to enable you to read and

write Russian, Arabic, Chinese, and other languages written in non-Roman scripts.

To read and write a language on your computer, it needs three things:

1. A character set for the script in which the language is written

2. A font for the character set

3. An operating system and application software that understand the

character set

If you want to write in the script as well as read it, you’ll also need an input method

for the script. However, XML defines character references that allow you to use

pure ASCII to encode characters not available in your native character set. This is

sufficient for an occasional quote in Greek or Chinese, although you wouldn’t want

to rely on it to write a novel in another language.

Putting the pieces together

XML defines the syntax for the tags you use to mark up a document. An XML docu-

ment is marked up with XML tags. The default character set for XML documents is

Unicode.

Cross-

Reference

Cross-

Reference

03 549863 Ch01.qxd 1/28/04 9:46 AM Page 15