Picked up a charcoal canister. While cleaning it up I checked the airflow of each port. All clear except the Dist Vac port that comes out of the cap that says Do Not Remove Cap. But I opened it in order to see if it was clogged. It appears to me that this particular port is not designed for air flow either direction. I conclude this only because it enters into a sealed area of the cap. I've seen a diagram in the TSM showing an arrow flow coming from the canister to the carb. Attaching many images from the TSM and the canister.
Question: what purpose is this port of it is truly sealed with no flow to our from the canister?