ABSTRACT
Letters (and the informal, internal kind of letter we call a memorandum) are the principal day-to-day medium of information exchange. This chapter is not about letter-writing in general, though much of what we say would apply to any letters; it is about letters written to give technical information, the type of letter likely to be written by the scientist or engineer working in an industrial or scientific organization. Other sorts of letters (in particular, sales letters) are not our province.
