[Requirement] Use SVG and PNG for graphics [Details] Use PNG for raster images, and SVG for all others. [Rationale] PNG is a much more capable format than other binary formats for raster images because it provides better compression, more options, and it's free. The best format you should require is SVG: it's scalable, XML-based, very light, and has a lot of capabilities, for example, animation using SMIL, which is supported on cell phones, etc. [Test tool] 
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