Return key

Return

Names	Return, Enter, Carriage Return
Symbol	↵
ASCII	0x0d, 0x0a (<CR>,<LF>), MacOS: 0x0d (<CR>) Unix,Amiga: 0x0a (<LF>)
USB	"Keyboard Return (ENTER)", page 7, id 40

A keyboard's Return key (often called Enter key on IBM-compatible PCs) does
(1) enter a new line and move the cursor to the start of that line or
(2) submit an input buffer to the host computer.

To be specific, "Return" refers to (1) and "Enter" refers to (2) but those functions are often overloaded on the same key with the meaning depending on the context. Additionally, the key is often used as an "OK button" to activate a dialog box' or menu's selected (or main) function.

On IBM-compatible PCs (starting with the Model F AT) the key has often been labelled with both the Return symbol ↵ and the text "Enter", indicating the key's both functions. As there has never been a textual "Return" legend on IBM PC keyboards, its key is often referred to as "Enter" and the ↵ symbol has often been misinterpreted as "the Enter symbol". Some IBM terminal and workstation keyboards have had separate Return and Enter keys.

On Macintosh, the Return key is called "Return", and specifically the Keypad-Enter key is referred to as the "Enter key".

Variants

Return key from a grey label Model M.

"Input Field" on an IBM Model F 122-key with German layout.

L-shaped enter on a Cherry G80-0778.

Underside of a "big-ass Enter" from a Cherry G80-0528.

Depending on the keyboard layout the return key has different shapes. The most common are:

ANSI

The US-ANSI keyboard layout (ANSI-INCITS 154-1988) has a horizontal Return key with the \ key above it. It is often 2.25u wide.

The horizontal Return key is preferred by many touch-typists over the vertical variant because it's left edge is closer to the centre and therefore easier to reach with the right pinky.

ISO and JIS

The ISO standard (ISO/IEC 9995-2) mandates a vertical Return key spanning two rows. The Japanese JIS standard (JIS X 6002-1980) uses the same key as ISO.

It is often 1.25u wide. Some have a step or gap to the ']' key, but it is more common to be use that space for key surface, being 0.25u wider in the top row. This latter variation is sometimes called "J-shaped".

The ISO enter is also known as European enter as most European standard layouts are based on the ISO layout.

Backwards L-shaped

A "backwards-L shaped" (or just "L-shaped") Return key is the union of the ISO and ANSI Return keys. The key is often called Big-ass Enter because of its size, or Asian enter because it is found on many East Asian keyboards.

There have been studies that have shown it to be easier to hit accurately than the ISO and ANSI Return keys.

However, with the backwards-L shaped Return key, the '\' key has to be relocated, often at the expense of having a smaller backspace or right shift key.

Many vintage PC keyboards with otherwise ANSI and ISO layouts have large Enter keys, in particular Alps SKCL/SKCM series and Alps clone boards from Asia. It is sometimes used as a compromise to please both ANSI and ISO typists, but it has been speculated that the main reason for the key is often not ergonomics but to reduce costs by having a more unified construction.

The stabiliser arrangement varies, even among keyboard with the same switches. There is often only one wire-stabiliser that is either vertical or horizontal, with the other bit stabilised with a slider or a dummy switch. Alps keyboards sometimes have a long horizontal (ANSI-style) stabiliser and one very short vertical. Very rarely do horizontal and vertical stabilisers overlap.

Downwards L-shaped

Another variant is to have a vertical Return key in the lower-right corner, to the right of the right Shift key. This variant is often merged with an ANSI-style shape, shaped like a Backwards L-shaped Return key but with the vertical portion spanning downwards instead of upwards.

There is often no key in front of the key's lower edge, allowing the vertical portion to be struck with less accuracy, perhaps using the side of the hand instead of a single finger. On some keyboards with this shape, the Return key is also higher than others.

This more unusual style is found mostly on typewriters, but also on e.g. some IBM and UNIVAC terminals and the Canon Cat.

The key directly above is often a Backspace key (as in Unix layout) or a Back-tab key mirroring the position of the Tab key on the other side of the keyboard.

• 

  ANSI Enter and 2u Backspace

• 

  ISO Enter and 2u Backspace

• 

  JIS Return key (identical to ISO Enter) and 1u Backspace

• 

  Backwards-L Return and 1u Backspace

• 

  ANSI

• 

  ISO/JIS

• 

  Backwards-L ("Big-ass")

• 

  Backwards-L ("Slim-ass"/"semi-big-ass")

History

The earliest known Return key was the Line key on Donald Murray's tape-puncher (1901) which produced a distinct 5-dot code on paper tape to be input into a telegraph. Murray intended to make telegraphing more like typing by using QWERTY keyboards instead of 5-key chorded keyboards as used for the Baudôt system before it. The Line key was located to the left of a small Space key.

The Blickensderfer Electric, also announced in 1901 had an electric return key: circular with a large 'L' (Left) key, located to the right of the 'P' key and a half row down. Typewriters would be produced both in Blickenserfer's DHIATENSOR layout as well as in QWERTY. After extensive marketing, the typewriter was eventually (probably) not introduced onto the market because of its high price and because electric voltage was not yet fully standardised ... or even available during daylight hours — as electricity was considered to be used for lighting only. (Some 1500 examples are believed to have been produced: they are considered to be the most desirable typewriters among collectors)

In 1929, the Electromatic typewriter was introduced with a key labelled Carriage Return. The key was circular, located one column to the right compared to on the Blickensderfer. Electromatic Typewriters Inc was bought by IBM in 1933 becoming its typewriter division. Later IBM Electric typewriters kept the key in the same position but it grew larger and rectangular, thus spanning two rows. The legend was shortened to Return in the US. In non-English language markets, a large outline right-arrow symbol was used instead, referring to the movement of the carriage.

Smith Corona released their first typewriter with powered carriage in 1960 with a key in the same position with a right-arrow and the wording Power Return.

The first generation of IBM Selectric typewriters in 1961 had a similar keyboard layout as its predecessors but with all rectangular keys fitted into a rectangle. The Return key was 1.5u wide with a 1.25u Backspace key above it. Non-English keyboards now used a left-arrow symbol referring to the movement of the type-ball.

The IBM Selectric II (1971) and Selectric III (1980) series came in variants with different Return keys and introduced the familiar ↵ symbol. On some Selectric II, the upper/left corner was shaved off for an additional key, turning the Return key into a Backwards-L with a very slim vertical part — the origin of the ANSI Return key. On some non-English language models, two keys were added, displacing and shrinking the Return key to 1u width — a prototype for the ISO/JIS Return key.

Meanwhile as typewriters evolved, the Teletype Corporation extended its Murray telegraph code with different codes - and keys - for horizontal-only carriage movement (<CR> - "Carriage Return") and feeding a new line (<LF> - "Line Feed"). Printers printed in real-time at the speed of transmission, and it was necessary to use two codes because the printer's mechanism would have been too slow for just one. Teletype equipment was used for input and output on early computers and this segregated convention was later inherited by the computer character sets EBCDIC and ASCII. Some early computer/terminal keyboards (especially those that produce ASCII directly) had separate (Carriage) Return and Line Feed keys. The Return key tended to be located as on typewriters, with the Line Feed key on the row below it. Many electric keyboards had short horizontal Return keys that did not require any stabilisers. Most systems these days use a single <LF> as end-of-line code in text encoding, except for Microsoft Windows PCs that still have <CR><LF> as its convention. Many Windows programs will produce a single <LF> if the Enter key is pressed with a modifier.

The now-standard Return keys are moved/shrunk versions of the Return key of the early electric typewriters. The ANSI key is halved in height, and the ISO/JIS key is displaced one column to the right. Compared to the Blickensderfer Electric, both are also displaced an additional column to the right.