#include <windows.h>

BOOL32 Arc
    HDC32 hdc,
    INT32 left,
    INT32 top,
    INT32 right,
    INT32 bottom,
    INT32 xstart,
    INT32 ystart,
    INT32 xend,
    INT32 yend


U16 array noValue
0 yend, y of endpoint
1 xend, x of endpoint
2 ystart, y of endpoint
3xstart, x of endpoint
4bottom, bottom of bounding box
5right, right of bounding box
6top, top of bounding box
7left, left of bounding box
left, right, top and bottom are the extents of the ellipse of which the arc is a part
xstart,ystart define a point from which you draw an imaginary line between it and the center of the ellipse, where that line intersects the ellipse is the starting part of the arc
xend,yend similiarly define the end of the arc.

This is quite different from how X, and other drawing lib's define an Arc, and its somewhat awkward to convert from it to X's mechanism, see the X bindings for libwmf for info on that.