[Inkscape-devel] Rationale of colour swatches

What is the rationale for the colour swatches? They appear roughly to follow the red/orange/yellow/green/blue/indigo/violet scheme. However, I'd like to know where the names etc come from.

The grey shades do not seem to follow the normal 10% values. I would expect nine shades between black and white rather than seven as shown. And personally I find 20% black to be more meaningful than "gainsboro" (if that is 20% black).

If someone can point me to notes I would be grateful.

I am using the win version.

thanks, Erik