Mystery track on boom

[aadewar]

Hello!
On our new-to us IF, we have found a track on the port side of the boom, with a block on either end, and a large cleat all the way aft.

I have little idea of what it is-can anybody help? I can see the aft block possibly being used in reefing (and there isn't any other normal way that I can see) but it seems odd.

Aaron

[maja]

Probably this is an arrangement for a 2-reef system.

[aadewar]

Thank you-I'll look at the mainsail tonight and count reef points!