BFC means Back Face Culling. See the related LDraw specification, and Wikipedia defintion.
The best way to have a feel for it is to look at a part LDView in BFC Mode (use BFC red back face / green front face option). If you see red, it means you see the facet from the wrong side. Have a look to a subpart (they are generally not closed so you may look "from inside")...
For your pattern, LPC does the work for you... you just have to change the "0 BFC NOCERTIFY" to "0 BFC CERTIFY CCW"
The best way to have a feel for it is to look at a part LDView in BFC Mode (use BFC red back face / green front face option). If you see red, it means you see the facet from the wrong side. Have a look to a subpart (they are generally not closed so you may look "from inside")...
For your pattern, LPC does the work for you... you just have to change the "0 BFC NOCERTIFY" to "0 BFC CERTIFY CCW"