I believe a carriage pin is like what is called a hitch pin down here or a hairpin in other areas. It has one flat straight side and the other is wavy, like a woman's bobby pin for her hair. The flat 'leg' goes into the hole, and the wavy 'leg' tends to grip on the out side of the hole to retain it in place.
Here is a link to pic of one. It is the one that has the wavy leg.
http://www2.northerntool.com/product..._200314150.htm
Here is a link to pic of one. It is the one that has the wavy leg.
http://www2.northerntool.com/product..._200314150.htm
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