Spare main halyard

Oct 23, 2013
9
Hunter 450 Passage Solomons Island, MD
I recently purchased a 2000 Hunter 450 Passage. Could someone enlighten me as to what the "Spare Main Halyard" line is? It enters the mast on the starboard side in the lowest sheave below the Main and staysail sheaves. It doesn't come down the mast. I have lowered the furling main and removed it to have the clew restitched/reinforced, so it isn't tied to the main. The port side of the mast has the spinnaker and foresail halyards.

Any enlightenment will be greatly appreciated.