I noticed that a lot of people on this thread are using the term 'enamel' for a lot of different paint types - even 2-pack types.
To me in Britain, 'enamels' are either stove enamel, which is a bit specialist but still available here, or the synthetic enamels (which I think are usually alkyd based).
We also have the choice of Cellulose Lacquer, Acrylic Lacquer (the most common one in the aerosols in most motor factor places now), alkyd enamel and 2-pack.
Our 2-pack is either the old iso-cyanate stuff or the newer water-based stuff which you can use with ordinary paint masks. Generally, the water-based stuff is used in a base/lacquer system with a harder 2-pack lacquer on top.

I was wondering if 'enamel' was a general catch-all US English term for a whole lot of different paint types?