A THIN man showed the card in his hand. In front of him stood a nurse carrying a thick book containing the names of the inmates entitled to receive special therapy. The nurse looks at the name on the card and matches it with the list in her reference book. She then prepares a certain dose of the liquid drug for her patient. Witnessed by the nurse, the man mixes the liquid with syrup. Then, in a gulp, he drinks it and leaves.

This is a common sig