Comment 1 for bug 555017

SVG limits colors to 8-bit RGB values in the sRGB colorspace. Inkscape needs to comply with that.

To work with colors outside of the average monitor's display capabilities, color management is used. Inkscape provides the CMS color picker to select a linked ICC color profile that describes some target output device's color capabilities. When values outside of those in sRGB are selected they get clipped in the fallback RGB values set in the file.

So inkscape is already allowing values to be outside of 0-255 sRGB, and does clip them as needed for display fallback. The values are determined by the details of the ICC profile and most commonly use 0.0 - 1.0 floating point for RGB ones, etc.