What do HC and HL (hamiltonian graph problems) stand for?

Hopefully, this question is fine.

I’m referring to the NP-complete problems regarding hamiltonian graphs.

  • I suppose the C in HC is from Cycle or Circuit. It seems like Circuit is more popular.
  • HL (called HAMPATH sometimes) is a bit more difficult. HL deals with hamiltonian paths (HP is already in use, of course). My best guess is that since path graphs are also called linear graphs, the L may stand for Linear. Another possibility is Line.