The fonts available within edit-on Pro depend on the Java VM and operating system used. There is no comon mechanism to add/remove fonts supported by the Java VM on a particular operating systems. However, Serif, SansSerif and Monospaced are the fonts available on all edit-on Pro officially supported Java VMs and operating systems. So, these three fonts are the least common denominator when using edit-on Pro on various platforms.

Please keep in mind, when loading the editor as it is shipped with the edit-on Pro installation/evaluation package, you will see three font names (Arial, Courier, Times) in the editor’s toolbar drop-down. This is because those three names were specified as default within the editor’s configuration file (config.xml) by using the font mapping feature. When you delete the <fontmapping>...</fontmapping> tag within the config.xml file different fonts (style + quantity) will be shown in the editor’s drop-down, as they depend on the fonts available through your Java VM.

As already highlighted above, there are three common fonts (Serif, SansSerif and Monospaced) support by edit-on Pro. However, there might be following case. Within your system it is necessary that the name "Arial" (let's assume Arial is your corporate font style) is available within the editor’s drop-down although this font is actually not supported by the Java VM you use. Therefore, edit-on Pro provides the font mapping feature which allows you to map a name (can be any name) shown in the editor’s drop-down to a font used for rendering in the editor’s WYSIWYG view and a font used for exporting, e.g. to display the document in a browser. For example, in case the font Arial is not available through your Java VM, you can map the name "Arial" to the "rendering" font SansSerif (available on all edit-on Pro officially supported Java VMs) and the "exporting" font  Arial (supported by any browser). In such case the definition within the config.xml would be as follows.

<fontmapping> 
          <renderedfont>SansSerif</renderedfont>
          <exportedfont>Arial</exportedfont>
</fontmapping>

So, the user/author has the impression to use Arial because the rendering of SanSerif within the editor’s WYSIWYG view and the rendering of Arial within e.g. a web-browser is very similar. For more information about font mapping, see the chapter 2.2 "Configuration File" of the integration manual.