Take on the Greenwich parking sign

Can somebody explain to me how to make sense of this sign?
Last week while driving through Greenwich, I came across a sign which
stated there was 12 hour parking allowed and later in the same sign
said it was enforced from 9am and 5pm. Now my math skills aren't as
great as they we're pre baby#3 but there are only eight hours of
enforcement for this, so you could leave your Winnebago parked there
for eternity because if a 12 hour parking limit is only enforced for
an 8 hour stretch daily, you can't ever get a ticket.