What is a reverse line feed?

Question

What I want to know is two points as below:

What is a reverse line feed?
What is the difference between reverse line feed and line feed?

Is there anyone can give me an example or make an explanation?

Reverse line feed is a character that can be sent to a printer to roll out the paper a bit so that invoices can be torn off. — Lloyd Powell, May 17 '12 at 15:12
@ThePower, Actually I think the line feed advanced the paper, then the printer paused, so the user could tear off the the form, then the printer issued reverse line feeds to re-set it to where it was before rolling the paper out. — Elliptical view, Dec 17 '18 at 22:32

score 6 · Accepted Answer · answered May 17 '12 at 15:13

6

A reverse line feed makes the cursor go back up to the previous line. A regular line feed makes the cursor go to the next line.

Edit: ThePower is correct, these terms originate from the days of line printers, "feed" meaning to feed the paper through the printer, in this case by one line, and reverse line feed moving the paper backwards by one line.

answered May 17 '12 at 15:13

Andrew N Carr

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So what is a half reverse line feed? If I don't use a line printers, the RLF is meaningless. So why so many manual pages in linux contain the RLF. What are they used for? – Alex Locanda May 17 '12 at 15:19
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The RLF character can be used to move the cursor on the screen. I'm not familiar with a half reverse line feed, perhaps it moves the cursor to the previous line without moving it to the beginning of the line? – Andrew N Carr May 17 '12 at 16:57

score 1 · Answer 2 · answered Dec 17 '18 at 22:29

Some earlier computer printers, were able to print subscripts and superscripts, and first did this by rolling up or down a half line, instead of a whole line.

For example, as found in this old printer manual.

Let's take a look at the related vertical commands:

     line feed  and  reverse      line feed, and  
half line feed  and  reverse half line feed


     Line feed goes down one      line.  Reverse goes up one      line.
Half line feed goes down one half line.  Reverse goes up one half line.

score 1 · Answer 3 · answered Jan 28 '23 at 13:58

A reverse line feed is a character, specifically U+008D REVERSE LINE FEED. It's a control character.

A regular line feed makes the cursor go to the beginning of the next line. In contrast, a reverse line feed makes the cursor go to the beginning of the previous line.

This character is hardly ever used in modern text files, but it still exists.

What is a reverse line feed?

3 Answers3