HTML and CSS Reference
In-Depth Information
If and when you need to include math markup, use the
xmlns
attribute
again to define the math namespace. So, for instance, you could use the
xmlns
attribute within some math-specific tag of your otherwise common
XHTML document (assuming the
MATH
element exists, of course):
<div xmlns="http://www.w3.org/1998/Math/MathML">x2/x</div>
In this case, the XML-compliant browser would use the
ht-
tp://www.w3.org/1998/Math/MathML
namespace to divine that this is
the MATH, not the XHTML, version of the
<div>
tag, and should therefore
be displayed as a division equation.
It would quickly become tedious if you had to embed the
xmlns
attribute
into each and every
<div>
tag anytime you wanted to show a division
equation in your document. A better wayparticularly if you plan to apply
it to many different elements in your documentis to identify and label
the namespace at the beginning of your document, and then refer to it
by that label as a prefix to the affected element in your document. For
example:
<html xmlns="http://www.w3.org/TR/xhtml1"
xmlns:math="http://www.w3.org/1998/Math/MathML">
The
math
namespace can now be abbreviated to "math" later in your
document. So the streamlined:
</math:div>x2/x</div>
now has the same effect as the lengthy earlier example of the math
<di-
v>
tag containing its own
xmlns
attribute.
The vast majority of XHTML authors will never need to define multiple
namespaces and so will never have to use fully qualified names contain-
ing the namespace prefix. Even so, you should understand that multiple
