[TUHS] Line Terminators in Text Files

Doug McIlroy doug at cs.dartmouth.edu
Thu Sep 7 01:24:10 AEST 2017


> does anyone know anything about the 1961 DoD 8-bit
> character set standard it refers to?
>
> This does not appear to say anything about LF vs "Newline" (as either a
> name or a function), though the 1986 version of ASCII deprecates it, so
> was most likely acknowledged in versions between these in response to
> practices on OSes such as Multics. ECMA-6:1973 acknowledges it

I wouldn't say the "practices" of Multics influenced the recognition
of NL in the ASCII standard, for Multics didn't go into use until
1970, while NL was specified by 1965 (see below) with direct
reference to the properties of equipment, not operating systems.
Just what equipment, I don't know. IBM Selectric perhaps?

I recall Multics discussions that specifically cited the standard,
in particular Joe Ossanna's liaison between Multics and the TTY 37
design team at Western Electric, circa 1967. Thus it is my
understanding that Multics was an early adopter of ASCII's NL
convention, not an influencer of it.

Quotation from "Proposed revised American standard for information
interchange", CACM 8 (April 1965) 207-214:

  The controls CR and LF are intended for printer equipment
  which requires separate combinations to return the carriage
  and feed a line.

  As an alternative, for equipment which uses a single combination
  for a combined carriage-return and line-feed operation
  (called New-Line), NL will be coded at FE 2 [LF]. Then FE 5
  [CR] will be regarded as Backspace BS.

  If the latter type of equipment has to interwork with the
  former, it may be necessary to take steps to introduce the
  CR character.

One might read the preceding paragraph as advice not only to
writers of driver software but also to a future standards
committee to undo the curious notion of regarding CR
as BS. Unix effectively took it both ways, and kept the
original meaning of CR.

doug


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