Plain text simply consists of the character codes corresponding to the characters it contains. Nowadays most computers (and certainly all ours) using ASCII character codes. Passing such a file directly to a printer results in the document being printed with the default hardware font. For the most part we print via queues and the queue software can provide extra facilities. For example the UNIX command print5_2up prints plain text with each sheet of paper receiving 2 pages of the document because the queue software passes the printer instructions to change fonts.