Entries 221-226 in tk.decls (the Tk_Outline function API) have no documentation anywhere in Tk. As part of the public API, this should be fixed.

    void Tk_CreateOutline(Tk_Outline *outline)
    void Tk_DeleteOutline(Display *display, Tk_Outline *outline)
    int Tk_ConfigOutlineGC(XGCValues *gcValues, Tk_Canvas canvas,
            Tk_Item *item, Tk_Outline *outline)
    int Tk_ChangeOutlineGC(Tk_Canvas canvas, Tk_Item *item,
            Tk_Outline *outline)
    int Tk_ResetOutlineGC(Tk_Canvas canvas, Tk_Item *item,
            Tk_Outline *outline)
    int Tk_CanvasPsOutline(Tk_Canvas canvas, Tk_Item *item,
            Tk_Outline *outline)