diff --git a/printed/corner_block.scad b/printed/corner_block.scad
index bf79d01..b9d20c1 100644
--- a/printed/corner_block.scad
+++ b/printed/corner_block.scad
@@ -24,6 +24,11 @@
 //! See [butt_box](#Butt_box) for an example of usage.
 //!
 //! Note that the block with its inserts is defined as a sub assembly, but its fasteners get added to the parent assembly.
+//!
+//! Specific fasteners can be omitted by setting a side's thickness to 0 and the block omitted by setting ```show_block``` to false.
+//! This allows the block and one set of fasteners to be on one assembly and the other fasteners on the mating assemblies.
+//!
+//! Star washers can be omitted by setting ```star_washers``` to false.
 //
 include <../core.scad>
 include <../vitamins/screws.scad>
diff --git a/printed/fixing_block.scad b/printed/fixing_block.scad
index d718106..1524280 100644
--- a/printed/fixing_block.scad
+++ b/printed/fixing_block.scad
@@ -24,6 +24,11 @@
 //! See [butt_box](#Butt_box) for an example of usage.
 //!
 //! Note that the block with its inserts is defined as a sub assembly, but its fasteners get added to the parent assembly.
+//!
+//! Specific fasteners can be omitted by setting a side's thickness to 0 and the block omitted by setting ```show_block``` to false.
+//! This allows the block and one set of fasteners to be on one assembly and the other fasteners on the mating assemblies.
+//!
+//! Star washers can be omitted by setting ```star_washers``` to false.
 //
 include <../core.scad>
 include <../vitamins/screws.scad>
diff --git a/readme.md b/readme.md
index 299b50d..363d0ec 100644
--- a/readme.md
+++ b/readme.md
@@ -3318,6 +3318,11 @@ See [butt_box](#Butt_box) for an example of usage.
 
 Note that the block with its inserts is defined as a sub assembly, but its fasteners get added to the parent assembly.
 
+Specific fasteners can be omitted by setting a side's thickness to 0 and the block omitted by setting ```show_block``` to false.
+This allows the block and one set of fasteners to be on one assembly and the other fasteners on the mating assemblies.
+
+Star washers can be omitted by setting ```star_washers``` to false.
+
 
 [printed/corner_block.scad](printed/corner_block.scad) Implementation.
 
@@ -3530,6 +3535,11 @@ See [butt_box](#Butt_box) for an example of usage.
 
 Note that the block with its inserts is defined as a sub assembly, but its fasteners get added to the parent assembly.
 
+Specific fasteners can be omitted by setting a side's thickness to 0 and the block omitted by setting ```show_block``` to false.
+This allows the block and one set of fasteners to be on one assembly and the other fasteners on the mating assemblies.
+
+Star washers can be omitted by setting ```star_washers``` to false.
+
 
 [printed/fixing_block.scad](printed/fixing_block.scad) Implementation.