 What are the tangler fields?
The ultimate should be the complete segregation of each specialization—social and genetic measures to make them breed true, because the unspecialized man is an uncivilized man, or at any rate he does not advance civilization. And letting the specializations mix would produce genetic undesirables: clerk-laborer or Professional-GI misfits, for example, being only half specialized, would be good at no specialization. And the basis of this specialization society was: "The aptitude groups are the true races of mankind." She was in a detachment of three unfortunates like herself, convoyed by an irritable guard, climbing the steel steps toward Block O from the floor below, when she heard the yelling.
 electronic fields near the floor to stop prisoners
 a type of uniform meant to keep the inmates secure  electronic fields in Block O that identify inmates  replacement for guards in Block O  electronic fields near the floor to stop prisoners