I assumed it was enamel, but I haven't actually checked.

The neat thing about RAL codes is that most of them have Pantone equivalents, so there's further matching you can do there, and if you have your frame custom painted, repainted, or powder coated, the new paint will almost always have an RAL or Pantone code.

If you have a keen eye, sometimes you can tell by sight. For example, last week I locked up my newly powder coated Trek right next to a brand new Disc Trucker and noticed that Surly's current "Super Dark Green" is- exactly- RAL 6012 'Black Green': the same shade of Royal Mail Green that I'd just had my Trek painted.