more help from Takuya

tutorial/t6.geo

@@ -27,7 +27,9 @@ Plane Surface(1) = {1};
 // Put 20 points with a refinement toward the extremities on curve 2
 Transfinite Line{2} = 20 Using Bump 0.05;
 
-// Put 20 points total on combination of curves l1, l2 and l3
+// Put 20 points total on combination of curves l1, l2 and l3 (beware
+// that the points p1 and p2 are shared by the curves, so we do not
+// create 6 + 6 + 10 = 22 points, but 20!)
 Transfinite Line{l1} = 6;
 Transfinite Line{l2} = 6;
 Transfinite Line{l3} = 10;

tutorial/t9.geo

@@ -24,7 +24,7 @@ Include "view3.pos" ;
 
 Plugin(Isosurface).Value = 0.67 ; // iso-value level
 Plugin(Isosurface).View = 0 ; // source view is View[0]
-Plugin(Isosurface).Run ; 
+Plugin(Isosurface).Run ; // run the plugin!
 
 // We also set some options for the `CutPlane' plugin (which computes
 // a section of a 3D view using the plane A*x+B*y+C*z+D=0), and then
@@ -50,6 +50,7 @@ Plugin(Annotate).FontSize = 28 ;
 Plugin(Annotate).Align = "Center" ; 
 Plugin(Annotate).View = 0 ;
 Plugin(Annotate).Run ; 
+
 Plugin(Annotate).Text = "(and a small subtitle)" ; 
 Plugin(Annotate).Y = 70 ; 
 Plugin(Annotate).Font = "Times-Roman" ;