standards at the minnesota renaissance festival (as i remember them), 1990 - 1993:

at the irish cottage: my johnny was a shoemaker, house husband's lament, julian of norwich, maid in the garrett, the chandler's shop, the chastity belt, the vicar and the frog

at the peasant parade: the peasants are sleeping (to the tune of when johnny comes marching home), rattlin' bog, ramblin' rover (by andy stewart), roll the old chariot along

at cast call: swing low sweet chariot

at the closing gate show: the mermaid song ("and the ocean waves do roll...")

the only expressly banned song that i knew of: greensleeves

but of course, it was generally frowned upon to sing any of the standards in places other than their rightful homes. authenticity was supposed to be medium strict: all oldish european folk, unless you wrote it yourself. clearly, though, that wasn't enforced. i once heard a band play "lincoln duncan" by paul simon, and a friend of mine would get lots of requests for "mona lisa is having a bad day" by michelle shocked.