Creating a plane by specifying two previously defined lines.
$$
$$ Declarations
$$
ENTITY/LN1,LN2,PL1
$$
$$ Geometry Definition
$$
LN1=LINE/1,0,-1,0
LN2=LINE/-1,1,1,-1,-1,1
$$
$$ Plane Definition
$$
PL1=PLANE/LN1,LN2
A Plane Specified by Two Lines