diff --git a/content/klc/S4.5.adoc b/content/klc/S4.5.adoc
index 93633941..763ee160 100644
--- a/content/klc/S4.5.adoc
+++ b/content/klc/S4.5.adoc
@@ -2,10 +2,14 @@
 brief = "Pins not connected on the footprint may be omitted from the symbol"
 +++
 
-Often a component has pins that are not physically connected, and in such cases, unconnected pins may be omitted from the schematic symbol.
+Often a component has pins that are not physically connected.
+Even these pins should be included in the symbol. Refer to the link:/libraries/klc/S4.6[requirements for hidden pins].
+
+However in some cases unconnected pins may be omitted from the schematic symbol.
 
 . Pins may only be omitted if they are never to be connected _under any circumstances_
+. Unconnected pins may only be omitted if including them would make the symbol unnecessarily large.
 . If pins are designated `NC` but the datasheet specifies that these must be pulled to ground or otherwise connected to a specific net, then these **must** be shown on the schematic symbol
-. If the pin-count in the schematic does not match the pad-count on the footprint, the footprint filter must include the pad-count of the footprint (see also link:/libraries/klc/S5.2[requirements for footprint filters])
-* `SOT?23?5`
-* `SOIC?8`
+. The footprint filter must include the pad count of the footprint if the symbol has omitted pins (see also link:/libraries/klc/S5.2[requirements for footprint filters])
+* `BGA?144`
+* `QFN?20`
diff --git a/content/klc/S4.6.adoc b/content/klc/S4.6.adoc
index d8363b95..792d2811 100644
--- a/content/klc/S4.6.adoc
+++ b/content/klc/S4.6.adoc
@@ -2,13 +2,14 @@
 brief = "Hidden pins"
 +++
 
-Hidden connection pins are generally not allowed for schematic symbols. Any connection point must be visible, otherwise unexpected net connections can occur.
+Hidden symbol pins are generally not allowed for schematic symbols. Any connection point must be visible, otherwise unexpected net connections can occur.
 
-Hidden power pins are also not allowed.
 
 **Exceptions**
 
-. Unused NC pins can be set to invisible. In this case the electrical type must be `Not Connected`. The end of the pin should lie on the symbols outline box to prevent unwanted connections to the invisible pin (see screenshot below).
+. Power input pins must not be invisible unless used in power symbols (hidden power input pins are global labels). Refer to the link:/libraries/klc/S4.3[requirements for pin stacking]
+. Pins that are not intended to be connected must be set to invisible. In this case the electrical type must be `Not Connected`. The end of the pin should lie within or on the symbols outline to prevent unwanted connections to the invisible pin (see screenshot below).
+* Pins specified as not connected may be shown if they are expected to be connected in a significant number of usecases. (Example: The datasheet suggests them to be connected to ground or some other potential for better EMC behaviour.)
 . Invisible pins may be used in a pin stack to allow one-to-many connections. Refer to the link:/libraries/klc/S4.3[requirements for pin stacking]
 
-{{< klcimg src="S4.6" title="Hidden NC-pins in a symbol and hidden pins as part of a power-pin-stack" >}}
\ No newline at end of file
+{{< klcimg src="S4.6" title="Hidden NC-pins in a symbol and hidden pins as part of a power-pin-stack" >}}
diff --git a/content/libraries/klc.adoc b/content/libraries/klc.adoc
index 6d9fdb9e..2f980538 100644
--- a/content/libraries/klc.adoc
+++ b/content/libraries/klc.adoc
@@ -13,7 +13,7 @@ aliases = [ "/klc/" ]
 toc::[]
 
 
-**link:/libraries/klc/history/[Revision: 3.0.20]**
+**link:/libraries/klc/history/[Revision: 3.0.21]**
 
 ---
 
diff --git a/content/libraries/klc_history.adoc b/content/libraries/klc_history.adoc
index 504af09a..7e45a4e0 100644
--- a/content/libraries/klc_history.adoc
+++ b/content/libraries/klc_history.adoc
@@ -5,6 +5,10 @@ url = "/libraries/klc/history/"
 +++
 
 ---
+== 3.0.21 - 2019-09-01
+* Clarify rules regarding NC pins
+* Clarify handling of hidden pins
+
 == 3.0.20 - 2019-06-30
 * Update F9.1 screenshots and terms to match current GUI