What is a vertical tab?

What was the original histo开发者_如何学运维rical use of the vertical tab character (\v in the C language, ASCII 11)?

Did it ever have a key on a keyboard? How did someone generate it?

Is there any language or system still in use today where the vertical tab character does something interesting and useful?

Vertical tab was used to speed up printer vertical movement. Some printers used special tab belts with various tab spots. This helped align content on forms. VT to header space, fill in header, VT to body area, fill in lines, VT to form footer. Generally it was coded in the program as a character constant. From the keyboard, it would be CTRL-K.

I don't believe anyone would have a reason to use it any more. Most forms are generated in a printer control language like postscript.

@Talvi Wilson noted it used in python '\v'.

print("hello\vworld")

Output:

hello
     world

The above output appears to result in the default vertical size being one line. I have tested with perl "\013" and the same output occurs. This could be used to do line feed without a carriage return on devices with convert linefeed to carriage-return + linefeed.

Microsoft Word uses VT as a line separator in order to distinguish it from the normal new line function, which is used as a paragraph separator.

In the medical industry, VT is used as the start of frame character in the MLLP/LLP/HLLP protocols that are used to frame HL-7 data, which has been a standard for medical exchange since the late 80s and is still in wide use.

It was used during the typewriter era to move down a page to the next vertical stop, typically spaced 6 lines apart (much the same way horizontal tabs move along a line by 8 characters).

In modern day settings, the vt is of very little, if any, significance.

The ASCII vertical tab (\x0B)is still used in some databases and file formats as a new line WITHIN a field. For example:

• In the .mer file format to allow new lines within a data field,
• FileMaker databases can use vertical tabs as a linefeed (see https://support.microsoft.com/en-gb/kb/59096).

I have found that the VT char is used in pptx text boxes at the end of each line shown in the box in oder to adjust the text to the size of the box. It seems to be automatically generated by powerpoint (not introduced by the user) in order to move the text to the next line and fix the complete text block to the text box. In the example below, in the position of §:

"This is a text §
inside a text box"

A vertical tab was the opposite of a line feed i.e. it went upwards by one line. It had nothing to do with tab positions. If you want to prove this, try it on an RS232 terminal.

similar to R0byn's experience, i was experimenting with a Powerpoint slide presentation and dumped out the main body of text on the slide, finding that all the places where one would typically find carriage return (ASCII 13/0x0d/^M) or line feed/new line (ASCII 10/0x0a/^J) characters, it uses vertical tab (ASCII 11/0x0b/^K) instead, presumably for the exact reason that dan04 described above for Word: to serve as a "newline" while staying within the same paragraph. good question though as i totally thought this character would be as useless as a teletype terminal today.

I believe it's still being used, not sure exactly. There might be even a key combination of it.

As English is written Left to Right, Arabic Right to Left, there are languages in world that are also written top to bottom. In that case a vertical tab might be useful same as the horizontal tab is used for English text.

I tried searching, but couldn't find anything useful yet.