class Magick::RVG::PathData

def curveto(abs, x1, y1, x2, y2, x, y, *coords)

the coordinates are relative.
true the coordinates are absolute, otherwise
If abs is
Add a curveto (cubic Bezier) command.
def curveto(abs, x1, y1, x2, y2, x, y, *coords)
  @path << sprintf('%s%g,%g %g,%g %g,%g ', (abs ? 'C' : 'c'), x1, y1, x2, y2, x, y)
  # "multiple sets of coordinates may be specified to draw a polybezier"
  add_points(6, *coords)
end