Also, if you intend to enter a hexadecimal value, be sure to include the x prefix or it will be interpreted as a decimal value. If you enter a numerical character reference wrong, the number may resolve to a range in Unicode that does not have printable characters. If you misspell a named entity, it will not resolve. If only one entity is not resolving, it may simply be entered wrong. However, some browsers do not support all of these space characters, and may display a placeholder character instead of the intended space. In HTML output, these characters will pass through the stylesheet and be rendered in the output encoding for the HTML file. If you need to customize the width of any of those special space characters, you can change the stylesheet parameters that are defined in that module. The length unit used for the leaders is em, which scales to the current font size. So the print stylesheet uses a set of templates in the stylesheet module fo/spaces.xsl to convert them to fo:leader elements of different lengths. However, many print fonts do not support all of the characters in that range. For example, the characters in the Unicode range to represent spaces of different widths. Not all of these characters may work in the various output forms. Used to prevent a line break, as for example, after the hyphen in a word that contains its own hyphen. Used to allow a line break in a word without generating a hyphen. Space equal to the narrow punctuation of a font. One-sixth of an EM SPACE, similar to thin space.
![embeded lucida sans unicode embeded lucida sans unicode](http://muhammadanism.org/Nav/Images/FontProperties.gif)
One-fourth of an EM SPACE, called a mid space. One-third of an EM SPACE, called a thick space. Usually a space equal to the type size in points.
![embeded lucida sans unicode embeded lucida sans unicode](https://farm5.static.flickr.com/4016/4501787061_85cf79dbbd_o.png)
Space that may not be broken at the end of a line.