#impact_printer  a printer that prints by mechanical impacts
  supertype:  printing_machine__printer  a machine that prints
  subtype:  bar_printer__barprinter  an impact printer that uses a bar to carry the type slugs
  subtype:  chain_printer__chainprinter  an impact printer that carries the type slugs by links of a revolving chain
  subtype:  wire_matrix_printer__wire_printer__stylus_printer  an impact printer in which each character is represented by a pattern of dots made by wires or styli

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