diff --git a/attachments.scad b/attachments.scad
index c6c6780..298c2b1 100644
--- a/attachments.scad
+++ b/attachments.scad
@@ -504,8 +504,10 @@ module hulling(a)
 // Description:
 //   Takes a 3D mask shape, and attaches it to the given edges, with the appropriate orientation to be
 //   `diff()`ed away.  The mask shape should be vertically oriented (Z-aligned) with the back-right
-//   quadrant (X+Y+) shaped to be diffed away from the edge of parent attachable shape.  For a more
-//   step-by-step explanation of attachments, see the [[Attachments Tutorial|Tutorial-Attachments]].
+//   quadrant (X+Y+) shaped to be diffed away from the edge of parent attachable shape.
+//   For details on specifying the edges to mask see [Specifying Edges](edges.scad#section-specifying-edges).
+//   For a step-by-step explanation of attachments, see the [[Attachments Tutorial|Tutorial-Attachments]].
+//   
 // Figure: A Typical Edge Rounding Mask
 //   module roundit(l,r) difference() {
 //       translate([-1,-1,-l/2])
@@ -515,8 +517,8 @@ module hulling(a)
 //   }
 //   roundit(l=30,r=10);
 // Arguments:
-//   edges = Edges to mask.  See the docs for [`edges()`](edges.scad#edges) to see acceptable values.  Default: All edges.
-//   except = Edges to explicitly NOT mask.  See the docs for [`edges()`](edges.scad#edges) to see acceptable values.  Default: No edges.
+//   edges = Edges to mask.  See [Specifying Edges](edges.scad#section-specifying-edges).  Default: All edges.
+//   except = Edges to explicitly NOT mask.  See [Specifying Edges](edges.scad#section-specifying-edges).  Default: No edges.
 // Side Effects:
 //   Sets `$tags = "mask"` for all children.
 // Example:
@@ -574,7 +576,7 @@ module edge_mask(edges=EDGES_ALL, except=[]) {
 //           }
 module corner_mask(corners=CORNERS_ALL, except=[]) {
     assert($parent_geom != undef, "No object to attach to!");
-    corners = corners(corners, except=except);
+    corners = _corners(corners, except=except);
     vecs = [for (i = [0:7]) if (corners[i]>0) CORNER_OFFSETS[i]];
     for (vec = vecs) {
         vcount = (vec.x?1:0) + (vec.y?1:0) + (vec.z?1:0);
@@ -630,11 +632,13 @@ module face_profile(faces=[], r, d, convexity=10) {
 // See Also: attachable(), position(), attach(), face_profile(), corner_profile()
 // Description:
 //   Takes a 2D mask shape and attaches it to the selected edges, with the appropriate orientation and
-//   extruded length to be `diff()`ed away, to give the edge a matching profile.  For a more step-by-step
+//   extruded length to be `diff()`ed away, to give the edge a matching profile.
+//   For details on specifying the edges to mask see [Specifying Edges](edges.scad#section-specifying-edges).
+//   For a step-by-step
 //   explanation of attachments, see the [[Attachments Tutorial|Tutorial-Attachments]].
 // Arguments:
-//   edges = Edges to mask.  See the docs for [`edges()`](edges.scad#edges) to see acceptable values.  Default: All edges.
-//   except = Edges to explicitly NOT mask.  See the docs for [`edges()`](edges.scad#edges) to see acceptable values.  Default: No edges.
+//   edges = Edges to mask.  See [Specifying Edges](edges.scad#section-specifying-edges).  Default: All edges.
+//   except = Edges to explicitly NOT mask.  See [Specifying Edges](edges.scad#section-specifying-edges).  Default: No edges.
 //   convexity = Max number of times a line could intersect the perimeter of the mask shape.  Default: 10
 // Side Effects:
 //   Sets `$tags = "mask"` for all children.
diff --git a/beziers.scad b/beziers.scad
index 40b3147..ffa61d4 100644
--- a/beziers.scad
+++ b/beziers.scad
@@ -1276,7 +1276,7 @@ function bezier_patch(patch, splinesteps=16, style="default") =
 //          [[0, 10, 8.75], [0, 5, 8.75], [0, 0, 8.75], [-5, 0, 8.75], [-10, 0, 8.75]],
 //          [[0, 10, 2.5], [0, 5, 2.5], [0, 0, 2.5], [-5, 0, 2.5], [-10, 0, 2.5]]
 //         ];
-//   vnf_wireframe((bezier_patch(patch, splinesteps)),d=0.1);
+//   vnf_wireframe((bezier_patch(patch, splinesteps)),width=0.1);
 //   color("red")move_copies(flatten(patch)) sphere(r=0.3,$fn=9);
 // Example(3D): With bezier_patch_degenerate the degenerate point does not have excess triangles.  The top half of the patch decreases the number of sampled points by 2 for each row.  
 //   splinesteps=8;
@@ -1287,7 +1287,7 @@ function bezier_patch(patch, splinesteps=16, style="default") =
 //          [[0, 10, 8.75], [0, 5, 8.75], [0, 0, 8.75], [-5, 0, 8.75], [-10, 0, 8.75]],
 //          [[0, 10, 2.5], [0, 5, 2.5], [0, 0, 2.5], [-5, 0, 2.5], [-10, 0, 2.5]]
 //         ];
-//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),d=0.1);
+//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),width=0.1);
 //   color("red")move_copies(flatten(patch)) sphere(r=0.3,$fn=9);
 // Example(3D): With splinesteps odd you get one "odd" row where the point count decreases by 1 instead of 2.  You may prefer even values for splinesteps to avoid this. 
 //   splinesteps=7;
@@ -1298,7 +1298,7 @@ function bezier_patch(patch, splinesteps=16, style="default") =
 //          [[0, 10, 8.75], [0, 5, 8.75], [0, 0, 8.75], [-5, 0, 8.75], [-10, 0, 8.75]],
 //          [[0, 10, 2.5], [0, 5, 2.5], [0, 0, 2.5], [-5, 0, 2.5], [-10, 0, 2.5]]
 //         ];
-//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),d=0.1);
+//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),width=0.1);
 //   color("red")move_copies(flatten(patch)) sphere(r=0.3,$fn=9);
 // Example(3D): A more extreme degeneracy occurs when the top half of a patch is degenerate to a line.  (For odd length patches the middle row must be degenerate to trigger this style.)  In this case the number of points in each row decreases by 1 for every row.  It doesn't matter of splinesteps is odd or even. 
 //   splinesteps=8;
@@ -1308,7 +1308,7 @@ function bezier_patch(patch, splinesteps=16, style="default") =
 //            repeat([0,0,5],5),
 //            repeat([0,0,10],5)
 //           ];
-//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),d=0.1);
+//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),width=0.1);
 //   color("red")move_copies(flatten(patch)) sphere(r=0.3,$fn=9);
 // Example(3D): Here is a degenerate cubic patch.
 //   splinesteps=8;
@@ -1318,7 +1318,7 @@ function bezier_patch(patch, splinesteps=16, style="default") =
 //              repeat([0,0,30],4)
 //               ];
 //   color("red")move_copies(flatten(patch)) sphere(r=0.3,$fn=9);
-//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),d=0.1);
+//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),width=0.1);
 // Example(3D): A more extreme degenerate cubic patch, where two rows are equal.
 //   splinesteps=8;
 //   patch = [ [ [-20,0,0], [-10,0,0],[0,10,0],[0,20,0] ],
@@ -1327,13 +1327,13 @@ function bezier_patch(patch, splinesteps=16, style="default") =
 //              repeat([-10,10,30],4)          
 //           ];
 //   color("red")move_copies(flatten(patch)) sphere(r=0.3,$fn=9);
-//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),d=0.1);
+//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),width=0.1);
 // Example(3D): Quadratic patch degenerate at the right side:
 //   splinesteps=8;
 //   patch = [[[0, -10, 0],[10, -5, 0],[20, 0, 0]],
 //            [[0, 0, 0],  [10, 0, 0], [20, 0, 0]],
 //            [[0, 0, 10], [10, 0, 5], [20, 0, 0]]];
-//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),d=0.1);
+//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),width=0.1);
 //   color("red")move_copies(flatten(patch)) sphere(r=0.3,$fn=9);
 // Example(3D): Cubic patch degenerate at both ends.  In this case the point count changes by 2 at every row.  
 //   splinesteps=8;
@@ -1343,7 +1343,7 @@ function bezier_patch(patch, splinesteps=16, style="default") =
 //            [ [-20,0,10], [-10,0,10],[0,10,10],[0,20,10] ],
 //            repeat([-10,10,20],4),
 //           ];
-//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),d=0.1);
+//   vnf_wireframe(bezier_patch_degenerate(patch, splinesteps),width=0.1);
 //   color("red")move_copies(flatten(patch)) sphere(r=0.3,$fn=9);
 function bezier_patch_degenerate(patch, splinesteps=16, reverse=false, return_edges=false) =
     !return_edges ? bezier_patch_degenerate(patch, splinesteps, reverse, true)[0] :
diff --git a/shapes3d.scad b/shapes3d.scad
index 5a128e2..bd49ae7 100644
--- a/shapes3d.scad
+++ b/shapes3d.scad
@@ -89,24 +89,26 @@ function cube(size=1, center, anchor, spin=0, orient=UP) =
 //   cuboid(size, p1=, ...);
 //   cuboid(p1=, p2=, ...);
 // Usage: Chamfered Cubes
-//   cuboid(size, [chamfer=], [edges=], [except_edges=], [trimcorners=], ...);
+//   cuboid(size, [chamfer=], [edges=], [except=], [trimcorners=], ...);
 // Usage: Rounded Cubes
-//   cuboid(size, [rounding=], [edges=], [except_edges=], [trimcorners=], ...);
+//   cuboid(size, [rounding=], [edges=], [except=], [trimcorners=], ...);
 // Usage: Attaching children
 //   cuboid(size, [anchor=], ...) [attachments];
 //
 // Description:
-//   Creates a cube or cuboid object, with optional chamfering or rounding.
-//   Negative chamfers and roundings can be applied to create external masks,
-//   but only apply to edges around the top or bottom faces.
+//   Creates a cube or cuboid object, with optional chamfering or rounding of edges and corners.  
+//   Negative chamfers and roundings can be applied to create external fillets, but they 
+//   but only apply to edges around the top or bottom faces.  If you specify an edge set other than "ALL"
+//   with such roundings or chamfers then you will get an error.  See
+//   [Specifying Edges](edges.scad#section-specifying-edges) for information on how to specify edge sets.  
 //
 // Arguments:
 //   size = The size of the cube.
 //   ---
 //   chamfer = Size of chamfer, inset from sides.  Default: No chamfering.
 //   rounding = Radius of the edge rounding.  Default: No rounding.
-//   edges = Edges to chamfer/round.  See the docs for [`edges()`](edges.scad#edges) to see acceptable values.  Default: All edges.
-//   except = Edges to explicitly NOT chamfer/round.  See the docs for [`edges()`](edges.scad#edges) to see acceptable values.  Default: No edges.
+//   edges = Edges to mask.  See [Specifying Edges](edges.scad#section-specifying-edges).  Default: all edges.
+//   except = Edges to explicitly NOT mask.  See [Specifying Edges](edges.scad#section-specifying-edges).  Default: No edges.
 //   trimcorners = If true, rounds or chamfers corners where three chamfered/rounded edges meet.  Default: `true`
 //   p1 = Align the cuboid's corner at `p1`, if given.  Forces `anchor=ALLNEG`.
 //   p2 = If given with `p1`, defines the cornerpoints of the cuboid.
@@ -230,8 +232,8 @@ module cuboid(
     edges = _edges(edges, except=first_defined([except_edges,except]));
     assert(is_vector(size,3));
     assert(all_positive(size));
-    assert(is_undef(chamfer) || is_finite(chamfer));
-    assert(is_undef(rounding) || is_finite(rounding));
+    assert(is_undef(chamfer) || is_finite(chamfer),"chamfer must be a finite value");
+    assert(is_undef(rounding) || is_finite(rounding),"rounding must be a finite value");
     assert(is_undef(p1) || is_vector(p1));
     assert(is_undef(p2) || is_vector(p2));
     assert(is_bool(trimcorners));