A name that has long since been mentioned in relation to the graphics behind Xenon (the development name for XBOX 360) is R500. Although this name has appeared from various sources, the actual development name ATI uses for Xenon's graphics is "C1", whilst the more "PR friendly" codename that has surfaced is "Xenos". ATI are probably fairly keen not to use the R500 name as this draws parallels with their upcoming series of PC graphics processors starting with R520, however R520 and Xenos are very distinct parts. R520's aim is obviously designed to meet the needs of the PC space and have Shader Model 3.0 capabilities as this is currently the highest DirectX API specification available on the PC, and as such these new parts still have their lineage derived from the R300 core, with discrete Vertex and Pixel Shaders; Xenos, on the other hand, is a custom design specifically built to address the needs and unique characteristics of the game console. ATI had a clean slate with which to design on and no specified API to target. These factors have led to the Unified Shader design, something which ATI have prototyped and tested prior to its eventual implementation ( with the rumoured R400 development ? ) , with capabilities that don't fall within any corresponding API specification. Whilst ostensibly Xenos has been hailed as a Shader Model 3.0 part, its capabilities don't fall directly inline with it and exceed it in some areas giving this more than a whiff of WGF2.0 (Windows Graphics Foundation 2.0 - the new name for DirectX Next / DirectX 10) about it.