Disc

**Figure 17:** disc made of four 90 degree segments
$\begin{figure}\epsfig{file=disc.eps,width=12cm}\end{figure}$
 PNT py      -0.00000        1.00000        0.00000 
 PNT p0      -0.00000       -0.00000        0.00000 
 PNT P001     0.70711       -0.00000       -0.70711 
 PNT P003    -0.00000       -0.00000       -1.00000 
 PNT P005    -0.70711       -0.00000       -0.70711 
 PNT P006    -1.00000       -0.00000        0.00000 
 PNT P009    -0.70711       -0.00000        0.70711 
 PNT P00A     0.00000       -0.00000        1.00000 
 PNT P00G     0.70711       -0.00000        0.70711 
 PNT P00I     1.00000       -0.00000       -0.00000 
 LINE L001 P00I P001 p0 4              
 LINE L002 P001 P003 p0 4              
 LINE L003 P003 p0 8              
 LINE L004 p0 P00I 8              
 LINE L005 P003 P005 p0 4              
 LINE L006 P005 P006 p0 4              
 LINE L007 P006 p0 8              
 LINE L009 P006 P009 p0 4              
 LINE L00A P009 P00A p0 4              
 LINE L00C P00A p0 8              
 LINE L00G P00A P00G p0 4              
 LINE L00I P00G P00I p0 4              
 GSUR A001 + BLEND  - L003 - L002 - L001 - L004 
 GSUR A002 + BLEND  - L007 - L006 - L005 + L003 
 GSUR A003 + BLEND  - L00C - L00A - L009 + L007 
 GSUR A004 + BLEND  + L004 - L00I - L00G + L00C 
 ELTY all QU4