TRACK_FILL_REF(R,FIX,I1,K))

• R is a LAYOUT.
• FIX(1:6) is a ray to be tracked from I1 to the end of the LAYOUT (or all around).
• I1 is the integer position of the first FIBRE.
• K is an INTERNAL_STATE.

On each node of the layout the entrance coordinates $(x,y)$ are stored on the node $(T\%REF(1),T\%REF(2))$ . The exit coordinate are on $(T\%REF(3),T\%REF(4))$.