Can you help ID this deck fitting?

[Cevin c Taylor]

These two fittings are on the port side of the deck, by the two portholes on my 1983 CP-16.  They are attached by screws w/ nuts on the inside.  I don't know what these are for.  There are no similar ones on the starboard side.  My guess is that it is maybe to run a line up to the boom to control it while running - but that's just a guess, and I'm a total novice in this.  It seems that if that's what it's for, there would be one on each side.  Can anyone help me out?

[Billy]

Those are jam cleats.
Probably for either a halyard, and a jib downhaul.

Maybe for tune jib sheets.

[Cevin c Taylor]

Thanks, I should have taken a better picture and shown that there are fittings a bit farther back for the jib sheets.  These are much newer than the ones above in the pic, and might have been placed there by the previous owner.