Originally Posted by FBinNY

Yes, there's a crown race seat, which is usually (but not always) one with the fork. Crown race is a press fit onto the seat.

While that is the normal system, there are variations. For example some sealed bearing headsets don't use a press on crown race, but instead have a split cone, which engages the lower bearing race and compresses onto the fork, the same way the top centering cone does.

If you're unsure, a photo will help, but you should be able to dope it out if you review a few tutorials.