Pikchr tracks colors as 24-bit RGB values. Black is 0. White is 16777215. Other color values are in between these two extremes.
Pikchr understands C-style hexadecimal numeric literals. So it is often convenient to express colors using 6-digit hex constants like 0x000000 or 0xffffff (for black and white respectively) rather than as base-10 literals.
Pikchr knows the names of the 140 standard HTML color names. If you use one of those color names in an expression, Pikchr will substitute the corresponding RGB value. For example, if you write:
circle "Hi" fill Bisque
That is the equivalent of writing:
circle "Hi" fill 0xffe4c4
Because 0xffe4c4 is the 24-bit RGB value for "Bisque".
To put it another way, Pikchr treats the keyword "Bisque" as an alternative spelling for the numeric literal 0xffe4c4.