Question: Brave new world: What is the system for labelling?

Are you referring the their caste system?

The caste system in BNW is separated into Alpha, Beta, Gamma, Delta, or Epsilon. The Alpha embryos are destined to become the leaders and thinkers of the World State. Each of the succeeding castes is conditioned to be slightly less physically and intellectually impressive. The Beta are usually high functioning socialites. They accept everything that they have been taught. They live to satisfy their desires; they think and act in a superficial manner. Lenina Crowne, (beta) is baffled by Bernard's (alpha) constantly questioning the nature of things. Bernard Marx (note the irony in the name) thinks on a more abstract level. Alpha's have this ability but are not encouraged to use it in the context that Bernard does.