Bruce,
What is JFSS? for us unknowledgeable ones (or maybe non- North American?)
Interestinly in my Scots Gaelic Dict. port (what puirt comes from, I think being used as a plural) port is dance music or a reel, and a jig is port-cruinn or damhsa -cruinn, basically a round dance.
Now in Irish the word port is used to describe a jig, and ríl is used to describe a reel. The reason I automatically went for the literal translaion of "mouth jig" is because I speak Irish not Scots, and the one purt a beul I know is jig. Strange how the languages have diverged over the type of dance described. So yes, Scots would either think of it as vocal dance music or vocal reel.
Benjamin