Allows user control of how basic fontnames are represented in SVG output. If fontnames is undefined or "svg", the output will try to use known SVG fontnames. For example, the default font "Times-Roman" will be mapped to the basic SVG font "serif". This can be overridden by setting fontnames to "ps" or "gd". In the former case, known PostScript font names such as "Times-Roman" will be used in the output. In the latter case, the fontconfig font conventions are used. Thus, "Times-Roman" would be treated as "Nimbus Roman No9 L". These last two options are useful with SVG viewers that support these richer fontname spaces.