Many of XHTML's attributes use a set of standard data types such as lengths, names, and so on. The following sections describe these standard data types.
To specify a linear dimension, you can use any of these forms:
A number by itself is interpreted as a number of pixels.
A number followed by a percent sign (
%) is interpreted as some percentage of available
space. For example, if an element fills the width of
the screen, the length “
50%” would mean half the width of the screen.
When describing the columns of a table, you can
specify their widths as a number followed by an
*). The available width is
then parceled out proportionally among those
numbers. For example, if you specify the widths of
the columns of a three-column table as “
2*”, and “
first column would get 1/6 of the available width,
the second column would get 1/3 (2/6), and the third
column would get half (3/6).