I think the confusion stems from your use of the term "Code Zero". A Code Zero sail is a very large sail, similar to an asymmetric spinnaker, but with a low-stretch line integrated into the luff. The integral line in the luff allows the sail to be flown with a taut luff to higher wind angles than a typical asymmetric chute, and also allows it to be deployed and doused with a furler system. It is normally flown as the foremost sail, forward of the genoa, while close-beam reaching in moderate wind conditions.
Based on the information you provided above, my best guess is that the sail you are describing is either a spinnaker forestaysail ('staysail) or another sort of 'staysail with an integral stay. The spinnaker 'staysail is sometimes flown in conjunction with the conventional spinnaker when reaching (as opposed to running deep). Unlike most conventional 'staysails that are hoisted on the forestay, these sails are set on the fly. With the integral "stay" sewn into the luff, it gets tacked to a deck pad eye and then hoisted from its bag by the 'staysail halyard.
Spinnaker staysails are not too commonly seen these days, but on boats of your era they were not unusual. However, the two-to-one purchase at the head of halyard (which allows the luff/stay to be cranked nice and tight with a conventional mast/halyard winch) suggests to me that this might be more of an upwind/reaching 'staysail, rather than a spinnaker 'staysail (which does not usually require a very tight luff).
Hope this helps some.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Pacific Seacraft Crealock 31 #62
NEVER CALLS CRUISINGDAD BACK....CAN"T TAKE THE ACCENT