text: draft.mixins.system = {
    // Cartesian:
    // - page.system('cartesian')
    // - (x, y)
    // - x is right, y is up, z is out of the page (right-hand)
    // - global origin (0, 0) is at bottom-left
    //
    // Polar:
    // - page.system('polar')
    // - (r, φ)
    // - φ is counter-clockwise, with 0 pointing to the right
    // - global pole (0, 0) is at center
    //
    // BACKLOG:30 remove svg coordinates?
    // Web/SVG:
    // - page.system('web')
    // - (x, y)
    // - x is right, y is down, z is out of the page (left-hand)
    // - global origin (0, 0) is at top-left
  
    // BACKLOG:10 switch φ for θ?
    // BACKLOG:0 Spherical (ρ, θ, φ), Cylindrical (ρ, φ, z)
    system(system) {
      /* if (this.prop('system') != system) {
        // BACKLOG:20 recursively convert all elements to new system?
      } */
      return this.prop('system', system);
    }
  };
  
  draft.defaults.system = 'cartesian';
  