Standard file formats
RFC 678
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RFC - Unknown
(December 1974; No errata)
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2013-03-02
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RFC 678 (Unknown)
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Network Working Group J. Postel
Request for Comments: 678 (SRI-ARC)
NIC: 31524 19 December 1974
Standard File Formats
Introduction
In an attempt to provide online documents to the network community we
have had many problems with the physical format of the final
documents. Much of this difficulty lies in the fact that we do not
have control or even knowledge of all the processing steps or devices
that act on the document file. A large part of the difficulty in the
past has been due to some assumptions we made about the rest of the
world being approximately like our own environment. We now see that
the problems are due to differing assumptions and treatment of files
to be printed as documents. We therefore propose to define certain
standard formats for files and describe the expected final form for
printed copies of such files.
These standard formats are not additional File Transfer Protocol data
types/modes/structures, but rather usage descriptions between the
originator and ultimate receiver of the file. It may be useful or
even necessary at some hosts to construct programs that convert files
between common local formats and the standard formats specified here.
The intent is that the author of a document may prepare his/her text
and store it in an online file, then advertise that file by name and
format (as specified here), such that interested individuals may copy
and print the file with full understanding of the characteristics of
the format controls and the logical page size.
Standardization Elements
The elements or aspects of a file to be standardized are the
character or code set used, the format control procedures, the area
of the page to be used for text, and the method to describe
overstruck or underlined characters.
The area of the page to be used for text can be confusing to discuss,
in an attempt to be clear we define a physical page and a logical
page. Please note that the main emphasis of this note is to describe
the standard formats in terms of the logical page, and that it is up
to each site to map the logical page onto the physical page of each
of their devices.
- 1 -
Standard File Formats
Standardization Elements
Physical Page
The physical page is the medium that carries the text, the
height and width of its area are measured in inches.
The typical physical page is a piece of paper eleven inches
high and eight and one half inches wide.
Typical print density is 10 characters per inch
horizontally and 6 characters per inch vertically. This
results in the typical physical page having a maximum
capacity of 66 lines and 85 characters per line. It is
often the case that printing devices limit the area of
the physical page by enforcing margins.
Logical Page
The logical page is the area that can contain text, the height
of this area is measured in lines and the width is measured in
characters.
A typical logical page is 60 lines high and 72 characters
wide.
Code Set
The character encoding will be the network standard Network
Virtual Terminal (NVT) code as used in Telnet and File Transfer
protocols, that is ASCII in an eight bit byte with the high order
bit zero.
Format Control
The format will be controlled by the ASCII format effectors:
Form Feed <FF>
Moves the printer to the top of the next logical page
keeping the same horizontal position.
Carriage Return <CR>
Moves the printer to the left edge of the logical page
remaining on current line.
- 2 -
Standard File Formats
Standardization Elements
Line Feed <LF>
Moves the printer to the next print line, keeping the same
horizontal position.
Horizontal Tab <HT>
Moves the printer to the next horizontal tab stop.
The conventional stops for horizontal tabs are every
eight characters, that is character positions 9, 17, 25,
... within the logical page.
Note that it is difficult to enforce these conventions and
it is therefore recommended that horizontal tabs not be used
in document files.
Vertical Tab <VT>
Moves the printer to the next vertical tab stop.
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