+++
brief = "Symbol outline and fill requirements"
+++

. Symbol body must have a line width of `10mil` (`0.254mm`)
. Black-box symbols (e.g. ICs with hidden functionality) should be filled with background color
. Simple components (e.g. discrete components or those with a _distinctive shape_) should not be filled with background color

*Fill background*

{{< klcimg src="S3.3a" title="Fill background for black-box symbols" >}}

*Do not fill*

{{< klcimg src="S3.3b" title="Simple symbols may remain unfilled" >}}