diff --git a/joiners.scad b/joiners.scad
index e13e2b4..b6c8ebb 100644
--- a/joiners.scad
+++ b/joiners.scad
@@ -1,6 +1,6 @@
 //////////////////////////////////////////////////////////////////////
 // LibFile: joiners.scad
-//   Snap-together joiners.
+//   Modules for joining separately printed parts including screw together, snap-together and dovetails. 
 // Includes:
 //   include <BOSL2/std.scad>
 //   include <BOSL2/joiners.scad>
@@ -19,11 +19,12 @@ include <rounding.scad>
 // Description:
 //   Creates a mask to clear an area so that a half_joiner can be placed there.
 // Usage:
-//   half_joiner_clear(h, w, [a], [clearance], [overlap])
+//   half_joiner_clear(h, w, [a], [clearance=], [overlap=]) [ATTACHMENTS];
 // Arguments:
 //   h = Height of the joiner to clear space for.
 //   w = Width of the joiner to clear space for.
 //   a = Overhang angle of the joiner.
+//   ---
 //   clearance = Extra width to clear.
 //   overlap = Extra depth to clear.
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
@@ -31,6 +32,7 @@ include <rounding.scad>
 //   orient = Vector to rotate top towards, after spin.  See [orient](attachments.scad#subsection-orient).  Default: `UP`
 // Example:
 //   half_joiner_clear();
+function half_joiner_clear(h=20, w=10, a=30, clearance=0, overlap=0.01, anchor=CENTER, spin=0, orient=UP) = no_function("half_joiner_clear");
 module half_joiner_clear(h=20, w=10, a=30, clearance=0, overlap=0.01, anchor=CENTER, spin=0, orient=UP)
 {
     dmnd_height = h*1.0;
@@ -62,7 +64,7 @@ module half_joiner_clear(h=20, w=10, a=30, clearance=0, overlap=0.01, anchor=CEN
 
 // Module: half_joiner()
 // Usage:
-//   half_joiner(h, w, l, [a], [screwsize], [guides], [$slop])
+//   half_joiner(h, w, l, [a], [screwsize=], [guides=], [$slop=]) [ATTACHMENTS];
 // Description:
 //   Creates a half_joiner object that can be attached to half_joiner2 object.
 // Arguments:
@@ -70,6 +72,7 @@ module half_joiner_clear(h=20, w=10, a=30, clearance=0, overlap=0.01, anchor=CEN
 //   w = Width of the half_joiner.
 //   l = Length of the backing to the half_joiner.
 //   a = Overhang angle of the half_joiner.
+//   ---
 //   screwsize = Diameter of screwhole.
 //   guides = If true, create sliding alignment guides.
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
@@ -79,6 +82,7 @@ module half_joiner_clear(h=20, w=10, a=30, clearance=0, overlap=0.01, anchor=CEN
 // Examples(FlatSpin,VPD=75):
 //   half_joiner(screwsize=3);
 //   half_joiner(h=20,w=10,l=10);
+function half_joiner(h=20, w=10, l=10, a=30, screwsize=undef, guides=true, anchor=CENTER, spin=0, orient=UP) = no_function("half_joiner");
 module half_joiner(h=20, w=10, l=10, a=30, screwsize=undef, guides=true, anchor=CENTER, spin=0, orient=UP)
 {
     dmnd_height = h*1.0;
@@ -141,7 +145,7 @@ module half_joiner(h=20, w=10, l=10, a=30, screwsize=undef, guides=true, anchor=
 
 // Module: half_joiner2()
 // Usage:
-//   half_joiner2(h, w, l, [a], [screwsize], [guides])
+//   half_joiner2(h, w, l, [a], [screwsize=], [guides=])
 // Description:
 //   Creates a half_joiner2 object that can be attached to half_joiner object.
 // Arguments:
@@ -149,6 +153,7 @@ module half_joiner(h=20, w=10, l=10, a=30, screwsize=undef, guides=true, anchor=
 //   w = Width of the half_joiner.
 //   l = Length of the backing to the half_joiner.
 //   a = Overhang angle of the half_joiner.
+//   ---
 //   screwsize = Diameter of screwhole.
 //   guides = If true, create sliding alignment guides.
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
@@ -157,6 +162,7 @@ module half_joiner(h=20, w=10, l=10, a=30, screwsize=undef, guides=true, anchor=
 // Examples(FlatSpin,VPD=75):
 //   half_joiner2(screwsize=3);
 //   half_joiner2(h=20,w=10,l=10);
+function half_joiner2(h=20, w=10, l=10, a=30, screwsize=undef, guides=true, anchor=CENTER, spin=0, orient=UP) = no_function("half_joiner2");
 module half_joiner2(h=20, w=10, l=10, a=30, screwsize=undef, guides=true, anchor=CENTER, spin=0, orient=UP)
 {
     dmnd_height = h*1.0;
@@ -193,11 +199,12 @@ module half_joiner2(h=20, w=10, l=10, a=30, screwsize=undef, guides=true, anchor
 // Description:
 //   Creates a mask to clear an area so that a joiner can be placed there.
 // Usage:
-//   joiner_clear(h, w, [a], [clearance], [overlap])
+//   joiner_clear(h, w, [a], [clearance=], [overlap=]) [ATTACHMENTS];
 // Arguments:
 //   h = Height of the joiner to clear space for.
 //   w = Width of the joiner to clear space for.
 //   a = Overhang angle of the joiner.
+//   ---
 //   clearance = Extra width to clear.
 //   overlap = Extra depth to clear.
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
@@ -205,6 +212,7 @@ module half_joiner2(h=20, w=10, l=10, a=30, screwsize=undef, guides=true, anchor
 //   orient = Vector to rotate top towards, after spin.  See [orient](attachments.scad#subsection-orient).  Default: `UP`
 // Example:
 //   joiner_clear();
+function joiner_clear(h=40, w=10, a=30, clearance=0, overlap=0.01, anchor=CENTER, spin=0, orient=UP) = no_function("joiner_clear");
 module joiner_clear(h=40, w=10, a=30, clearance=0, overlap=0.01, anchor=CENTER, spin=0, orient=UP)
 {
     dmnd_height = h*0.5;
@@ -225,7 +233,7 @@ module joiner_clear(h=40, w=10, a=30, clearance=0, overlap=0.01, anchor=CENTER,
 
 // Module: joiner()
 // Usage:
-//   joiner(h, w, l, [a], [screwsize], [guides], [$slop])
+//   joiner(h, w, l, [a], [screwsize=], [guides=], [$slop=]) [ATTACHMENTS];
 // Description:
 //   Creates a joiner object that can be attached to another joiner object.
 // Arguments:
@@ -233,6 +241,7 @@ module joiner_clear(h=40, w=10, a=30, clearance=0, overlap=0.01, anchor=CENTER,
 //   w = Width of the joiner.
 //   l = Length of the backing to the joiner.
 //   a = Overhang angle of the joiner.
+//   ---
 //   screwsize = Diameter of screwhole.
 //   guides = If true, create sliding alignment guides.
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
@@ -242,6 +251,7 @@ module joiner_clear(h=40, w=10, a=30, clearance=0, overlap=0.01, anchor=CENTER,
 // Examples(FlatSpin,VPD=125):
 //   joiner(screwsize=3);
 //   joiner(w=10, l=10, h=40);
+function joiner(h=40, w=10, l=10, a=30, screwsize=undef, guides=true, anchor=CENTER, spin=0, orient=UP) = no_function("joiner");
 module joiner(h=40, w=10, l=10, a=30, screwsize=undef, guides=true, anchor=CENTER, spin=0, orient=UP)
 {
     attachable(anchor,spin,orient, size=[w, 2*l, h]) {
@@ -262,13 +272,14 @@ module joiner(h=40, w=10, l=10, a=30, screwsize=undef, guides=true, anchor=CENTE
 // Description:
 //   Creates a mask to clear an area so that a pair of joiners can be placed there.
 // Usage:
-//   joiner_pair_clear(spacing, [n], [h], [w], [a], [clearance], [overlap])
+//   joiner_pair_clear(spacing, [n], [h], [w], [a], [clearance=], [overlap=]) [ATTACHMENTS];
 // Arguments:
 //   spacing = Spacing between joiner centers.
+//   n = Number of joiners (2 by default) to clear for.
 //   h = Height of the joiner to clear space for.
 //   w = Width of the joiner to clear space for.
 //   a = Overhang angle of the joiner.
-//   n = Number of joiners (2 by default) to clear for.
+//   ---
 //   clearance = Extra width to clear.
 //   overlap = Extra depth to clear.
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
@@ -277,7 +288,8 @@ module joiner(h=40, w=10, l=10, a=30, screwsize=undef, guides=true, anchor=CENTE
 // Examples:
 //   joiner_pair_clear(spacing=50, n=2);
 //   joiner_pair_clear(spacing=50, n=3);
-module joiner_pair_clear(spacing=100, h=40, w=10, a=30, n=2, clearance=0, overlap=0.01, anchor=CENTER, spin=0, orient=UP)
+function joiner_pair_clear(spacing=100, n=2, h=40, w=10, a=30, clearance=0, overlap=0.01, anchor=CENTER, spin=0, orient=UP) = no_function("joiner_pair_clear");
+module joiner_pair_clear(spacing=100, n=2, h=40, w=10, a=30, clearance=0, overlap=0.01, anchor=CENTER, spin=0, orient=UP)
 {
     dmnd_height = h*0.5;
     dmnd_width = dmnd_height*tan(a);
@@ -296,16 +308,17 @@ module joiner_pair_clear(spacing=100, h=40, w=10, a=30, n=2, clearance=0, overla
 
 // Module: joiner_pair()
 // Usage:
-//   joiner_pair(h, w, l, [a], [screwsize], [guides], [$slop])
+//   joiner_pair(spacing, [n], h, w, l, [a], [alternate=], [screwsize=], [guides=], [$slop=]) [ATTACHMENTS];
 // Description:
 //   Creates a joiner_pair object that can be attached to other joiner_pairs .
 // Arguments:
 //   spacing = Spacing between joiner centers.
+//   n = Number of joiners in a row.  Default: 2
 //   h = Height of the joiners.
 //   w = Width of the joiners.
 //   l = Length of the backing to the joiners.
 //   a = Overhang angle of the joiners.
-//   n = Number of joiners in a row.  Default: 2
+//   ---
 //   alternate = If true (default), each joiner alternates it's orientation.  If alternate is "alt", do opposite alternating orientations.
 //   screwsize = Diameter of screwhole.
 //   guides = If true, create sliding alignment guides.
@@ -319,6 +332,7 @@ module joiner_pair_clear(spacing=100, h=40, w=10, a=30, n=2, clearance=0, overla
 //   joiner_pair(spacing=50, l=10, n=3, alternate=false);
 //   joiner_pair(spacing=50, l=10, n=3, alternate=true);
 //   joiner_pair(spacing=50, l=10, n=3, alternate="alt");
+function joiner_pair(spacing=100, h=40, w=10, l=10, a=30, n=2, alternate=true, screwsize=undef, guides=true, anchor=CENTER, spin=0, orient=UP) = no_function("joiner_pair");
 module joiner_pair(spacing=100, h=40, w=10, l=10, a=30, n=2, alternate=true, screwsize=undef, guides=true, anchor=CENTER, spin=0, orient=UP)
 {
     attachable(anchor,spin,orient, size=[spacing+w, 2*l, h]) {
@@ -344,14 +358,15 @@ module joiner_pair(spacing=100, h=40, w=10, l=10, a=30, n=2, alternate=true, scr
 // Description:
 //   Creates a mask to clear an area so that a pair of joiners can be placed there.
 // Usage:
-//   joiner_quad_clear(spacing, [n], [h], [w], [a], [clearance], [overlap])
+//   joiner_quad_clear([xspacing|spacing1=],[yspacing|spacing2=], [n], [h], [w], [a], [clearance], [overlap]) [ATTACHMENTS];
 // Arguments:
-//   spacing1 = Spacing between joiner centers.
-//   spacing2 = Spacing between back-to-back pairs/sets of joiners.
+//   spacing1 / xspacing = Spacing between joiner centers.
+//   spacing2 / yspacing = Spacing between back-to-back pairs/sets of joiners.
+//   n = Number of joiners in a row.  Default: 2
 //   h = Height of the joiner to clear space for.
 //   w = Width of the joiner to clear space for.
 //   a = Overhang angle of the joiner.
-//   n = Number of joiners in a row.  Default: 2
+//   ---
 //   clearance = Extra width to clear.
 //   overlap = Extra depth to clear.
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
@@ -360,7 +375,8 @@ module joiner_pair(spacing=100, h=40, w=10, l=10, a=30, n=2, alternate=true, scr
 // Examples:
 //   joiner_quad_clear(spacing1=50, spacing2=50, n=2);
 //   joiner_quad_clear(spacing1=50, spacing2=50, n=3);
-module joiner_quad_clear(xspacing=undef, yspacing=undef, spacing1=undef, spacing2=undef, n=2, h=40, w=10, a=30, clearance=0, overlap=0.01, anchor=CENTER, spin=0, orient=UP)
+function joiner_quad_clear(xspacing=undef, yspacing=undef, n=2, h=40, w=10, a=30, spacing1=undef, spacing2=undef, clearance=0, overlap=0.01, anchor=CENTER, spin=0, orient=UP)=no_function("joiner_quad_clear");
+module joiner_quad_clear(xspacing=undef, yspacing=undef, n=2, h=40, w=10, a=30, spacing1=undef, spacing2=undef, clearance=0, overlap=0.01, anchor=CENTER, spin=0, orient=UP)
 {
     spacing1 = first_defined([spacing1, xspacing, 100]);
     spacing2 = first_defined([spacing2, yspacing, 50]);
@@ -378,16 +394,18 @@ module joiner_quad_clear(xspacing=undef, yspacing=undef, spacing1=undef, spacing
 
 // Module: joiner_quad()
 // Usage:
-//   joiner_quad(h, w, l, [a], [screwsize], [guides], [$slop])
+//   joiner_quad([xspacing|spacing1=], [yspacing|spacing2=], [n], h, w, l, [a], [alternate=], [screwsize=], [guides=], [$slop=]) [ATTACHMENTS];
 // Description:
 //   Creates a joiner_quad object that can be attached to other joiner_pairs .
 // Arguments:
-//   spacing = Spacing between joiner centers.
+//   spacing1 / xspacing = Spacing between joiner centers.
+//   spacing2 / yspacing = Spacing between back-to-back pairs/sets of joiners.
+//   n = Number of joiners in a row.  Default: 2
 //   h = Height of the joiners.
 //   w = Width of the joiners.
 //   l = Length of the backing to the joiners.
 //   a = Overhang angle of the joiners.
-//   n = Number of joiners in a row.  Default: 2
+//   ---
 //   alternate = If true (default), joiners on each side alternate orientations.  If alternate is "alt", do opposite alternating orientations.
 //   screwsize = Diameter of screwhole.
 //   guides = If true, create sliding alignment guides.
@@ -401,6 +419,7 @@ module joiner_quad_clear(xspacing=undef, yspacing=undef, spacing1=undef, spacing
 //   joiner_quad(spacing1=50, spacing2=50, l=10, n=3, alternate=false);
 //   joiner_quad(spacing1=50, spacing2=50, l=10, n=3, alternate=true);
 //   joiner_quad(spacing1=50, spacing2=50, l=10, n=3, alternate="alt");
+function joiner_quad(spacing1=undef, spacing2=undef, xspacing=undef, yspacing=undef, h=40, w=10, l=10, a=30, n=2, alternate=true, screwsize=undef, guides=true, anchor=CENTER, spin=0, orient=UP) = no_function("joiner_quad");
 module joiner_quad(spacing1=undef, spacing2=undef, xspacing=undef, yspacing=undef, h=40, w=10, l=10, a=30, n=2, alternate=true, screwsize=undef, guides=true, anchor=CENTER, spin=0, orient=UP)
 {
     spacing1 = first_defined([spacing1, xspacing, 100]);
@@ -421,7 +440,7 @@ module joiner_quad(spacing1=undef, spacing2=undef, xspacing=undef, yspacing=unde
 // Module: dovetail()
 //
 // Usage:
-//   dovetail(gender, w|width, h|height, slide, [slope|angle], [taper|back_width], [chamfer], [r|radius], [round], [extra], [$slop])
+//   dovetail(gender, w=|width, h=|height, slide, [slope=|angle=], [taper=|back_width=], [chamfer=], [r=|radius=], [round=], [extra=], [$slop=])
 //
 // Description:
 //   Produces a possibly tapered dovetail joint shape to attach to or subtract from two parts you wish to join together.
@@ -500,6 +519,7 @@ module joiner_quad(spacing1=undef, spacing2=undef, xspacing=undef, yspacing=unde
 //   diff("remove")
 //     cuboid([50,30,10])
 //       position(TOP+BACK) xcopies(10,5) dovetail("female", slide=10, width=7, taper=4, height=4, $tags="remove",anchor=BOTTOM+FRONT,spin=180);
+function dovetail(gender, width, height, slide, h, w, angle, slope, taper, back_width, chamfer, extra=0.01, r, radius, round=false, anchor=BOTTOM, spin=0, orient) = no_function("dovetail");
 module dovetail(gender, width, height, slide, h, w, angle, slope, taper, back_width, chamfer, extra=0.01, r, radius, round=false, anchor=BOTTOM, spin=0, orient)
 {
     radius = get_radius(r1=radius,r2=r);
@@ -656,8 +676,8 @@ function _pin_size(size) =
 
 // Module: snap_pin()
 // Usage:
-//    snap_pin(size, [pointed], [anchor], [spin], [orient])
-//    snap_pin(r|radius|d|diameter, l|length, nub_depth, snap, thickness, [clearance], [preload], [pointed], [anchor], [spin], [orient])
+//    snap_pin(size, [pointed=], [anchor=], [spin=], [orient]=) [ATTACHMENTS];
+//    snap_pin(r=|radius=|d=|diameter=, l=|length=, nub_depth=, snap=, thickness=, [clearance=], [preload=], [pointed=]) [ATTACHMENTS];
 // Description:
 //    Creates a snap pin that can be inserted into an appropriate socket to connect two objects together.  You can choose from some standard
 //    pin dimensions by giving a size, or you can specify all the pin geometry parameters yourself.  If you use a standard size you can
@@ -674,6 +694,7 @@ function _pin_size(size) =
 //    and distributed under the Creative Commons - Attribution - Share Alike License
 // Arguments:
 //    size = text string to select from a list of predefined sizes, one of "standard", "small", or "tiny".
+//    ---
 //    pointed = set to true to get a pointed pin, false to get one with a rounded end.  Default: true
 //    r/radius = radius of the pin
 //    d/diameter = diameter of the pin
@@ -688,6 +709,7 @@ function _pin_size(size) =
 //    snap_pin("standard", anchor=CENTER, orient=UP, thickness = 1, $fn=40);
 // Example: Pins oriented for printing
 //    xcopies(spacing=10, n=4) snap_pin("standard", $fn=40);
+function snap_pin(size,r,radius,d,diameter, l,length, nub_depth, snap, thickness, clearance=0.2, preload, pointed=true, anchor=FRONT, spin=0, orient=FRONT, center) =no_function("snap_pin");
 module snap_pin(size,r,radius,d,diameter, l,length, nub_depth, snap, thickness, clearance=0.2, preload, pointed=true, anchor=FRONT, spin=0, orient=FRONT, center) {
   preload_default = 0.2;
   sizedat = _pin_size(size);
@@ -724,8 +746,8 @@ module snap_pin(size,r,radius,d,diameter, l,length, nub_depth, snap, thickness,
 
 // Module: snap_pin_socket()
 // Usage:
-//   snap_pin_socket(size, [fixed], [fins], [pointed], [anchor], [spin], [orient]);
-//   snap_pin_socket(r|radius|d|diameter, l|length, nub_depth, snap, [fixed], [pointed], [fins], [anchor], [spin], [orient])
+//   snap_pin_socket(size, [fixed=], [fins=], [pointed=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
+//   snap_pin_socket(r=|radius=|d=|diameter=, l=|length=, nub_depth=, snap=, [fixed=], [pointed=], [fins=]) [ATTACHMENTS];
 // Description:
 //   Constructs a socket suitable for a snap_pin with the same parameters.   If `fixed` is true then the socket has flat walls and the
 //   pin will not rotate in the socket.  If `fixed` is false then the socket is round and the pin will rotate, particularly well
@@ -739,6 +761,7 @@ module snap_pin(size,r,radius,d,diameter, l,length, nub_depth, snap, thickness,
 //   has a length of 6 and diameter of 3.2.  The "tiny" pin has a length of 4 and a diameter of 2.5.  
 // Arguments:
 //   size = text string to select from a list of predefined sizes, one of "standard", "small", or "tiny".
+//   ---
 //   pointed = set to true to get a pointed pin, false to get one with a rounded end.  Default: true
 //   r/radius = radius of the pin
 //   d/diameter = diameter of the pin
@@ -757,7 +780,8 @@ module snap_pin(size,r,radius,d,diameter, l,length, nub_depth, snap, thickness,
 //   diff("socket") cuboid([20,20,20]) {
 //     attach(TOP) snap_pin_socket("standard", $tags="socket");
 //     position(TOP+FRONT)snap_pin_socket("standard", $tags="socket");
-//   }  
+//   }
+function snap_pin_socket(size, r, radius, l,length, d,diameter,nub_depth, snap, fixed=true, pointed=true, fins=false, anchor=BOTTOM, spin=0, orient=DOWN) = no_function("snap_pin_socket");
 module snap_pin_socket(size, r, radius, l,length, d,diameter,nub_depth, snap, fixed=true, pointed=true, fins=false, anchor=BOTTOM, spin=0, orient=DOWN) {
   sizedat = _pin_size(size);
   radius = get_radius(r1=r,r2=radius,d1=d,d2=diameter,dflt=struct_val(sizedat,"diameter")/2);
@@ -791,7 +815,7 @@ module snap_pin_socket(size, r, radius, l,length, d,diameter,nub_depth, snap, fi
 
 // Module: rabbit_clip()
 // Usage:
-//   rabbit_clip(type, length, width, snap, thickness, depth, [compression], [clearance], [lock], [lock_clearance], [splineteps], [anchor], [orient], [spin])
+//   rabbit_clip(type, length, width, snap, thickness, depth, [compression=], [clearance=], [lock=], [lock_clearance=], [splineteps=], [anchor=], [orient=], [spin=]) [ATTACHMENTS];
 // Description:
 //   Creates a clip with two flexible ears to lock into a mating socket, or create a mask to produce the appropriate
 //   mating socket.  The clip can be made to insert and release easily, or to hold much better, or it can be
@@ -871,6 +895,7 @@ module snap_pin_socket(size, r, radius, l,length, d,diameter,nub_depth, snap, fi
 //   snap = depth of hollow on the side of the clip
 //   thickness = thickness of the clip "line"
 //   depth = amount to extrude clip (give extra room for the socket, about 0.4mm)
+//   ---
 //   compression = excess width at the "ears" to lock more tightly.  Default: 0.1
 //   clearance = extra space in the socket for easier insertion.  Default: 0.1
 //   lock = set to true to make a locking clip that may be irreversible.  Default: false
@@ -920,6 +945,10 @@ module snap_pin_socket(size, r, radius, l,length, d,diameter,nub_depth, snap, fi
 //         xscale(0.8)
 //         zcyl(l=20,r=13.5, $tags="remove",$fn=64);
 //   }
+
+function rabbit_clip(type, length, width,  snap, thickness, depth, compression=0.1,  clearance=.1, lock=false, lock_clearance=0,
+                   splinesteps=8, anchor, orient, spin=0) = no_function("rabbit_clip");
+
 module rabbit_clip(type, length, width,  snap, thickness, depth, compression=0.1,  clearance=.1, lock=false, lock_clearance=0,
                    splinesteps=8, anchor, orient, spin=0)
 {
diff --git a/polyhedra.scad b/polyhedra.scad
index 38fd491..45331fb 100644
--- a/polyhedra.scad
+++ b/polyhedra.scad
@@ -1,11 +1,12 @@
 //////////////////////////////////////////////////////////////////////
 // LibFile: polyhedra.scad
-//   Useful platonic, archimedian, and catalan polyhedra.
+//   Generate Platonic solids, Archimedian solids, Catalan polyhedra, the trapezohedron, and some stellated polyhedra.
+//   You can also stellate any of the polyhedra, select polyhedra by their characterics and position objects on polyhedra faces. 
 // Includes:
 //   include <BOSL2/std.scad>
 //   include <BOSL2/polyhedra.scad>
 // FileGroup: Parts
-// FileSummary: Platonic, Archimidean, Catalan, and stellated polyhedra.
+// FileSummary: Platonic, Archimidean, Catalan, and stellated polyhedra
 //////////////////////////////////////////////////////////////////////
 
 
@@ -36,9 +37,16 @@ function _unique_groups(m) = [
 
 
 // Module: regular_polyhedron()
-//
+// Usage: Selecting a polyhedron
+//   regular_polyhedron([name],[index=],[type=],[faces=],[facetype=],[hasfaces=],...) [CHILDREN];
+// Usage: Controlling the size and position of the polyhedron
+//   regular_polyhedron(..., [or=|r=|d=],[ir=],[mr=],[side=],[facedown=],[anchor=], ...) [CHILDREN];]
+// Usage: Other options that change the polyhedron or handling of children
+//   regular_polyhedron(..., [draw=], [rounding=], [stellate=], [repeat=], [rotate_children=]) [CHILDREN];
+// Usage: options only for the trapezohedron
+//   regular_polyhedron("trapezohedron", [longside=],[h=], ...) [CHILDREN];
 // Description:
-//   Creates a regular polyhedron with optional rounding.  Children are placed on the polyhedron's faces.
+//   Creates a regular polyhedron with optional rounding.  Children are placed on the polyhedron's faces.  (Note that this is not attachable.)
 //   .
 //   **Selecting the polyhedron:**
 //   You constrain the polyhedra list by specifying different characteristics, that must all be met
@@ -127,22 +135,19 @@ function _unique_groups(m) = [
 //   faces = Number of faces.
 //   facetype = Scalar or vector listing required type of faces as vertex count.  Polyhedron must have faces of every type listed and no other types.
 //   hasfaces = Scalar of vector list face vertex counts.  Polyhedron must have at least one of the listed types of face.
-//   side = Length of the smallest edge of the polyhedron.  Default: 1.
-//   ir = inner radius.  Polyhedron is scaled so it has the specified inner radius. Overrides side.
-//   mr = middle radius.  Polyhedron is scaled so it has the specified middle radius.  Overrides side.
-//   or = outer radius.   Polyhedron is scaled so it has the specified outer radius.  Overrides side.
-//   r = outer radius.  Overrides or.
-//   d = outer diameter.  Overrides or.
-//   anchor = Side of the origin to anchor to.  The bounding box of the polyhedron is aligned as specified.  Use directional constants from `constants.scad`.  Default: `CENTER`
-//   center = If given, overrides `anchor`.  A true value sets `anchor=CENTER`, false sets `anchor=UP+BACK+RIGHT`.
+//   side = Length of the smallest edge of the polyhedron.  Default: 1 (if no radius or diameter is given).  
+//   ir = inner radius.  Polyhedron is scaled so it has the specified inner radius. 
+//   mr = middle radius.  Polyhedron is scaled so it has the specified middle radius.  
+//   or / r / d = outer radius.   Polyhedron is scaled so it has the specified outer radius. 
+//   anchor = Side of the origin to anchor to.  The bounding box of the polyhedron is aligned as specified.  Default: `CENTER`
 //   facedown = If false display the solid in native orientation.  If true orient it with a largest face down.  If set to a vertex count, orient it so a face with the specified number of vertices is down.  Default: true.
 //   rounding = Specify a rounding radius for the shape.  Note that depending on $fn the dimensions of the shape may have small dimensional errors.
 //   repeat = If true then repeat the children to fill all the faces.  If false use only the available children and stop.  Default: true.
 //   draw = If true then draw the polyhedron.  If false, draw the children but not the polyhedron.  Default: true.
 //   rotate_children = If true then orient children normal to their associated face.  If false orient children to the parent coordinate system.  Default: true.
-//   stellate = Set to a number to erect a pyramid on every face of your polyhedron with the specified height.  The height is a multiple of the side length.  Default: false.
-//   longside = Specify the long side length for a trapezohedron.  Ignored for other shapes.
-//   h = Specify the height of the apex for a trapezohedron.  Ignored for other shapes.
+//   stellate = Set to a number to erect a pyramid of that height on every face of your polyhedron.  The height is a multiple of the side length.  Default: false.
+//   longside = Specify the long side length for a trapezohedron.  Invalid for other shapes.
+//   h = Specify the height of the apex for a trapezohedron.  Invalid for other shapes.
 //
 // Side Effects:
 //   `$faceindex` - Index number of the face
@@ -293,8 +298,7 @@ module regular_polyhedron(
     or=undef,
     r=undef,
     d=undef,
-    anchor=[0,0,0],
-    center=undef,
+    anchor=CENTER,
     rounding=0,
     repeat=true,
     facedown=true,
@@ -311,7 +315,7 @@ module regular_polyhedron(
         hasfaces=hasfaces, side=side,
         ir=ir, mr=mr, or=or,
         r=r, d=d,
-        anchor=anchor, center=center,
+        anchor=anchor, 
         facedown=facedown,
         stellate=stellate,
         longside=longside, h=h
@@ -548,11 +552,11 @@ _stellated_polyhedra_ = [
 // Function: regular_polyhedron_info()
 //
 // Usage:
-//   x = regular_polyhedron_info(info, ....);
+//   info = regular_polyhedron_info(info, ...);
 //
 // Description:
 //   Calculate characteristics of regular polyhedra or the selection set for regular_polyhedron().
-//   Invoke with the same arguments used by regular_polyhedron() and use the `info` argument to
+//   Invoke with the same polyhedron selection and size arguments used by {{regular_polyhedron()}} and use the `info` argument to
 //   request the desired return value. Set `info` to:
 //     * `"vnf"`: vnf for the selected polyhedron
 //     * `"vertices"`: vertex list for the selected polyhedron
@@ -569,6 +573,7 @@ _stellated_polyhedra_ = [
 //     * `"name"`: name of selected polyhedron
 //
 // Arguments:
+//   info = Desired information to return for the polyhedron
 //   name = Name of polyhedron to create.
 //   ---
 //   index = Index to select from polyhedron list.  Default: 0.
@@ -576,22 +581,15 @@ _stellated_polyhedra_ = [
 //   faces = Number of faces.
 //   facetype = Scalar or vector listing required type of faces as vertex count.  Polyhedron must have faces of every type listed and no other types.
 //   hasfaces = Scalar of vector list face vertex counts.  Polyhedron must have at least one of the listed types of face.
-//   side = Length of the smallest edge of the polyhedron.  Default: 1.
-//   ir = inner radius.  Polyhedron is scaled so it has the specified inner radius. Overrides side.
-//   mr = middle radius.  Polyhedron is scaled so it has the specified middle radius.  Overrides side.
-//   or = outer radius.   Polyhedron is scaled so it has the specified outer radius.  Overrides side.
-//   r = outer radius.  Overrides or.
-//   d = outer diameter.  Overrides or.
-//   anchor = Side of the origin to anchor to.  The bounding box of the polyhedron is aligned as specified.  Use directional constants from `constants.scad`.  Default: `CENTER`
-//   center = If given, overrides `anchor`.  A true value sets `anchor=CENTER`, false sets `anchor=UP+BACK+RIGHT`.
+//   side = Length of the smallest edge of the polyhedron.  Default: 1 (if no radius or diameter is given).
+//   or / r / d = outer radius.   Polyhedron is scaled so it has the specified outer radius or diameter. 
+//   mr = middle radius.  Polyhedron is scaled so it has the specified middle radius.  
+//   ir = inner radius.  Polyhedron is scaled so it has the specified inner radius. 
+//   anchor = Side of the origin to anchor to.  The bounding box of the polyhedron is aligned as specified.  Default: `CENTER`
 //   facedown = If false display the solid in native orientation.  If true orient it with a largest face down.  If set to a vertex count, orient it so a face with the specified number of vertices is down.  Default: true.
-//   rounding = Specify a rounding radius for the shape.  Note that depending on $fn the dimensions of the shape may have small dimensional errors.
-//   repeat = If true then repeat the children to fill all the faces.  If false use only the available children and stop.  Default: true.
-//   draw = If true then draw the polyhedron.  If false, draw the children but not the polyhedron.  Default: true.
-//   rotate_children = If true then orient children normal to their associated face.  If false orient children to the parent coordinate system.  Default: true.
-//   stellate = Set to a number to erect a pyramid on every face of your polyhedron with the specified height.  The height is a multiple of the side length.  Default: false.
-//   longside = Specify the long side length for a trapezohedron.  Ignored for other shapes.
-//   h = Specify the height of the apex for a trapezohedron.  Ignored for other shapes.
+//   stellate = Set to a number to erect a pyramid of that height on every face of your polyhedron.  The height is a multiple of the side length.  Default: false.
+//   longside = Specify the long side length for a trapezohedron.  Invalid for other shapes.
+//   h = Specify the height of the apex for a trapezohedron.  Invalid for other shapes.
 function regular_polyhedron_info(
     info=undef, name=undef,
     index=undef, type=undef,
@@ -599,14 +597,13 @@ function regular_polyhedron_info(
     hasfaces=undef, side=undef,
     ir=undef, mr=undef, or=undef,
     r=undef, d=undef,
-    anchor=[0,0,0], center=undef,
+    anchor=CENTER,
     facedown=true, stellate=false,
     longside=undef, h=undef  // special parameters for trapezohedron
 ) = let(
-        anchor = !is_undef(center) ? [0,0,0] : anchor,
-        argcount = num_defined([ir,mr,or,r,d])
+        argcount = num_defined([side,ir,mr,or,r,d])
     )
-    assert(argcount<=1, "You must specify only one of 'ir', 'mr', 'or', 'r', and 'd'")
+    assert(argcount<=1, "You must specify only one of 'side', 'ir', 'mr', 'or', 'r', and 'd'")
     let(  
         //////////////////////
         //Index values into the _polyhedra_ array
@@ -622,8 +619,7 @@ function regular_polyhedron_info(
         volume = 8,       // volume of unit polyhedron (data not validated, not used right now)
         vertices = 9,     // vertex list (in arbitrary order)
         //////////////////////
-        r = !is_undef(d) ? d/2 : r,
-        or = !is_undef(r) ? r : or,
+        or = get_radius(r=r,r1=or,d=d),
         stellate_index = search([name], _stellated_polyhedra_, 1, 0)[0],
         name = stellate_index==[] ? name : _stellated_polyhedra_[stellate_index][1],
         stellate = stellate_index==[] ? stellate : _stellated_polyhedra_[stellate_index][2],
@@ -667,14 +663,16 @@ function regular_polyhedron_info(
         ),
         valid_facedown = is_bool(facedown) || in_list(facedown, entry[facevertices])
     )
+    assert(name == "trapezohedron" || num_defined([longside,h])==0, "The 'longside' and 'h' parameters are only allowed with trapezohedrons")
     assert(valid_facedown,str("'facedown' set to ",facedown," but selected polygon only has faces with size(s) ",entry[facevertices]))
     let(
-        side = default(side,1),   // This default setting must occur after _trapezohedron is called
         scalefactor = (
             name=="trapezohedron" ? 1 : (
-                argcount == 0? side :
-                !is_undef(ir)? ir/entry[in_radius] :
-                !is_undef(mr)? mr/entry[mid_radius] : or/entry[out_radius]
+                argcount == 0? 1     // Default side=1 if no size info given
+              : is_def(side) ? side  
+              : is_def(ir) ? ir/entry[in_radius] 
+              : is_def(mr) ? mr/entry[mid_radius] 
+              :              or/entry[out_radius]
             ) / entry[edgelen]
         ),
         face_triangles = hull(entry[vertices]),
diff --git a/sliders.scad b/sliders.scad
index 5f18955..a983d9f 100644
--- a/sliders.scad
+++ b/sliders.scad
@@ -16,11 +16,12 @@
 // Description:
 //   Creates a slider to match a V-groove rail.
 // Usage:
-//   slider(l, w, h, [base], [wall], [ang], [$slop])
+//   slider(l, w, h, [base=], [wall=], [ang=], [$slop=]) [ATTACHMENTS];
 // Arguments:
 //   l = Length (long axis) of slider.
 //   w = Width of slider.
 //   h = Height of slider.
+//   ---
 //   base = Height of slider base.
 //   wall = Width of wall behind each side of the slider.
 //   ang = Overhang angle for slider, to facilitate supportless printig.
@@ -30,6 +31,7 @@
 //   $slop = The printer-specific slop value to make parts fit just right.
 // Example:
 //   slider(l=30, base=10, wall=4, $slop=0.2, spin=90);
+function slider(l=30, w=10, h=10, base=10, wall=5, ang=30, anchor=BOTTOM, spin=0, orient=UP) = no_function("slider");
 module slider(l=30, w=10, h=10, base=10, wall=5, ang=30, anchor=BOTTOM, spin=0, orient=UP)
 {
     full_width = w + 2*wall;
@@ -64,11 +66,12 @@ module slider(l=30, w=10, h=10, base=10, wall=5, ang=30, anchor=BOTTOM, spin=0,
 // Description:
 //   Creates a V-groove rail.
 // Usage:
-//   rail(l, w, h, [chamfer], [ang])
+//   rail(l, w, h, [chamfer=], [ang=]) [ATTACHMENTS];
 // Arguments:
 //   l = Length (long axis) of slider.
 //   w = Width of slider.
 //   h = Height of slider.
+//   ---
 //   chamfer = Size of chamfer at end of rail.
 //   ang = Overhang angle for slider, to facilitate supportless printig.
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `BOTTOM`
@@ -76,6 +79,7 @@ module slider(l=30, w=10, h=10, base=10, wall=5, ang=30, anchor=BOTTOM, spin=0,
 //   orient = Vector to rotate top towards, after spin.  See [orient](attachments.scad#subsection-orient).  Default: `UP`
 // Example:
 //   rail(l=100, w=10, h=10);
+function rail(l=30, w=10, h=10, chamfer=1.0, ang=30, anchor=BOTTOM, spin=0, orient=UP) = no_function("rail");
 module rail(l=30, w=10, h=10, chamfer=1.0, ang=30, anchor=BOTTOM, spin=0, orient=UP)
 {
     attack_ang = 30;
diff --git a/utility.scad b/utility.scad
index 5a92dfb..a429754 100644
--- a/utility.scad
+++ b/utility.scad
@@ -22,6 +22,8 @@
 // Description:
 //   Returns a string representing the type of the value.  One of "undef", "boolean", "number", "nan", "string", "list", "range", "function" or "invalid".
 //   Some malformed "ranges", like '[0:NAN:INF]' and '[0:"a":INF]', may be classified as "undef" or "invalid".
+// Arguments:
+//   x = value whose type to check
 // Example:
 //   typ = typeof(undef);  // Returns: "undef"
 //   typ = typeof(true);  // Returns: "boolean"
@@ -75,6 +77,8 @@ function is_type(x,types) =
 // See Also: typeof(), is_type(), is_str()
 // Description:
 //   Returns true if `x` is not `undef`.  False if `x==undef`.
+// Arguments:
+//   x = value to check
 // Example:
 //   bool = is_def(undef);  // Returns: false
 //   bool = is_def(false);  // Returns: true
@@ -90,6 +94,8 @@ function is_def(x) = !is_undef(x);
 // See Also: typeof(), is_type(), is_int(), is_def()
 // Description:
 //   Returns true if `x` is a string.  A shortcut for `is_string()`.
+// Arguments:
+//   x = value to check
 // Example:
 //   bool = is_str(undef);  // Returns: false
 //   bool = is_str(false);  // Returns: false
@@ -107,6 +113,8 @@ function is_str(x) = is_string(x);
 // See Also: typeof(), is_type(), is_str(), is_def()
 // Description:
 //   Returns true if the given value is an integer (it is a number and it rounds to itself).  
+// Arguments:
+//   n = value to check
 // Example:
 //   bool = is_int(undef);  // Returns: false
 //   bool = is_int(false);  // Returns: false
@@ -147,6 +155,8 @@ function all_integer(x) =
 // See Also: typeof(), is_type(), is_str(), is_def(), is_int()
 // Description:
 //   Returns true if a given value `x` is nan, a floating point value representing "not a number".
+// Arguments:
+//   x = value to check
 // Example:
 //   bool = is_nan(undef);  // Returns: false
 //   bool = is_nan(false);  // Returns: false
@@ -163,6 +173,8 @@ function is_nan(x) = (x!=x);
 // See Also: typeof(), is_type(), is_str(), is_def(), is_int(), is_nan()
 // Description:
 //   Returns true if a given value `x` is a finite number.
+// Arguments:
+//   x = value to check
 // Example:
 //   bool = is_finite(undef);  // Returns: false
 //   bool = is_finite(false);  // Returns: false
@@ -181,6 +193,8 @@ function is_finite(x) = is_num(x) && !is_nan(0*x);
 // See Also: typeof(), is_type(), is_str(), is_def(), is_int()
 // Description:
 //   Returns true if its argument is a range
+// Arguments:
+//   x = value to check
 // Example:
 //   bool = is_range(undef);   // Returns: false
 //   bool = is_range(false);   // Returns: false
@@ -198,6 +212,8 @@ function is_range(x) = !is_list(x) && is_finite(x[0]) && is_finite(x[1]) && is_f
 // See Also: typeof(), is_type(), is_str(), is_def(), is_int(), is_range()
 // Description:
 //   Returns true if its argument is a valid range (deprecated ranges excluded).
+// Arguments:
+//   x = value to check
 // Example:
 //   bool = is_range(undef);   // Returns: false
 //   bool = is_range(false);   // Returns: false
@@ -219,7 +235,7 @@ function valid_range(x) =
 // Description:
 //   Returns true if OpenSCAD supports function literals, and the given item is one.
 // Arguments:
-//   x = The value to check against.
+//   x = The value to check
 // Example:
 //   f = function (a) a==2;
 //   bool = is_func(f);  // Returns: true
@@ -307,7 +323,7 @@ function is_bool_list(list, length) =
 //   Otherwise, returns the value of `dflt`.
 // Arguments:
 //   v = Value to pass through if not `undef`.
-//   dflt = Value to return if `v` *is* `undef`.
+//   dflt = Value to return if `v` *is* `undef`.  Default: undef
 function default(v,dflt=undef) = is_undef(v)? dflt : v;
 
 
@@ -321,7 +337,7 @@ function default(v,dflt=undef) = is_undef(v)? dflt : v;
 //   If all items are `undef`, or list is empty, returns `undef`.
 // Arguments:
 //   v = The list whose items are being checked.
-//   recursive = If true, sublists are checked recursively for defined values.  The first sublist that has a defined item is returned.
+//   recursive = If true, sublists are checked recursively for defined values.  The first sublist that has a defined item is returned.  Default: false
 // Example:
 //   val = first_defined([undef,7,undef,true]);  // Returns: 7
 function first_defined(v,recursive=false,_i=0) =
@@ -396,7 +412,7 @@ function num_defined(v) =
 //   Returns true if any item in the given array is not `undef`.
 // Arguments:
 //   v = The list whose items are being checked.
-//   recursive = If true, any sublists are evaluated recursively.
+//   recursive = If true, any sublists are evaluated recursively.  Default: false
 // Example:
 //   bool = any_defined([undef,undef,undef]);    // Returns: false
 //   bool = any_defined([undef,42,undef]);       // Returns: true
@@ -415,7 +431,7 @@ function any_defined(v,recursive=false) =
 //   Returns true if all items in the given array are not `undef`.
 // Arguments:
 //   v = The list whose items are being checked.
-//   recursive = If true, any sublists are evaluated recursively.
+//   recursive = If true, any sublists are evaluated recursively.  Default: false
 // Example:
 //   bool = all_defined([undef,undef,undef]);    // Returns: false
 //   bool = all_defined([undef,42,undef]);       // Returns: false
@@ -492,7 +508,7 @@ function u_div(a,b) =
 //   bool = any(l);
 //   bool = any(l, func);   // Requires OpenSCAD 2021.01 or later.
 // Requirements:
-//   Requires OpenSCAD 2021.01 or later to use the `func=` argument.
+//   Requires OpenSCAD 2021.01 or later to use the `func` argument.
 // Description:
 //   Returns true if any item in list `l` evaluates as true.
 // Arguments:
@@ -525,7 +541,7 @@ function _any_bool(l, i=0, out=false) =
 //   bool = all(l);
 //   bool = all(l, func);   // Requires OpenSCAD 2021.01 or later.
 // Requirements:
-//   Requires OpenSCAD 2021.01 or later to use the `func=` argument.
+//   Requires OpenSCAD 2021.01 or later to use the `func` argument.
 // Description:
 //   Returns true if all items in list `l` evaluate as true.  If `func` is given a function liteal
 //   of signature (x), returning bool, then that function literal is evaluated for each list item.
@@ -823,7 +839,7 @@ function _valstr(x) =
 //   expected = The value that was expected.
 //   info = Extra info to print out to make the error clearer.
 // Example:
-//   assert_approx(1/3, 0.333333333333333, str("number=",1,", demon=",3));
+//   assert_approx(1/3, 0.333333333333333, str("number=",1,", denom=",3));
 module assert_approx(got, expected, info) {
     no_children($children);
     if (!approx(got, expected)) {
@@ -874,7 +890,7 @@ module assert_equal(got, expected, info) {
 
 // Module: shape_compare()
 // Usage:
-//   shape_compare([eps]) {test_shape(); expected_shape();}
+//   shape_compare([eps]) {TEST_SHAPE; EXPECTED_SHAPE;}
 // Topics: Error Checking, Debugging, Testing
 // See Also: assert_approx(), assert_equal()
 // Description:
@@ -889,6 +905,7 @@ module assert_equal(got, expected, info) {
 //       rotate_extrude() right_half(planar=true) circle(d=100);
 //   }
 module shape_compare(eps=1/1024) {
+    assert($children==2,"Must give exactly two children");
     union() {
         difference() {
             children(0);