...because of hardware restrictions the Rage128Pro has (extremely) limited GL_TEXTURE_RECTANGLE_EXT support.
1) The tex coords are ignored (the whole texture is always used).
2) Only one texture unit can be used (i.e no multi texture)
3) Only GL_QUADS are supported.
4) The destination geometry is inferred from the bounding rect of the quad vertices.
5) The textured rectangle is rendered with origin at upper-left.
Because of these limits, the Rage128Pro drivers do not export the extension GL_TEXTURE_RECTANGLE_EXT string.
On the positive side, even with these limitations it does provide the ability to render non-power-of-2 screen aligned textured rectangles of rgba or yuv data formats which is all that is needed in certain cases. Since this is marginally useful, it was decided to not silently fail if this type of rendering was requested.