XML syntax
There are a few more restrictions on XML than on HTML; they make
parsing of XML simpler.
Tags cannot be omitted
Unlike HTML, XML does not allow you to omit tags. This
guarantees that parsers know where elements end.
The following example is acceptable HTML, but not XML:
|
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<table> <tr> <td>Dog</td> <td>Cat <td>Mouse </table> |
To change this into well-formed XML, you need to add all the
missing end tags:
|
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<table> <tr> <td>Dog</td> <td>Cat</td> <td>Mouse</td> </tr> </table> |
Representing empty
elements
Empty elements cannot be represented in XML in the same way they
are in HTML. An empty element is one that is not used to mark up data,
so in HTML, there is no end tag. There are two ways to handle empty
elements:
-
Place a dummy tag immediately after the start tag. For
example:1<img href="picture.jpg"></img> -
Use a slash character at the end of the initial tag:
1<img href="picture.jpg"/>This tells a parser that the element consists only of one
tag.
XML is case sensitive
XML is case sensitive, which allows it to be used with non-Latin
alphabets. You must ensure that letter case matches in start and end
tags: <MyTag> and </Mytag> belong to two different
elements.
White space
White space within tags in XML is unchanged by parsers.
All elements must be
nested
All XML elements must be properly nested. All child elements
must be closed before their parent elements close.