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verification. (May 2013) |
A page break is a marker in an electronic document that tells the document interpreter that the content which follows is part of a new page. A page break causes a form feed to be sent to the printer during spooling of the document to the printer. Thus it is one of the elements that contributes to pagination.
Form feed is a page-breaking
ASCII
control character. It directs the
printer to eject the current
page and to continue printing at the top of another. Often, it will also cause a
carriage return. The form feed character code is defined as 12 (0xC in
hexadecimal), and may be represented as Ctrl+L or ^L. In a related use, Ctrl+L can be used to clear the screen in Unix shells such as
bash, or redraw screen in TUI programs like vi/emacs. In the
C programming language (and other languages derived from C), the form feed character is represented as
'\f'
.
Unicode also provides the character U+21A1 ↡ DOWNWARDS TWO HEADED ARROW as a printable symbol for a form feed (not as the form feed itself).
[1]
The form feed character is considered
whitespace by the
C character classification function isspace()
.
Form feed is seldom used when programming with modern printers in modern operating environments like
Windows,
Unix,
Linux or
macOS. Instead, form feeds are generated by having the printing program call a form feed
API function. For example, when printing using the
.NET Framework, the
PrintPageEventArgs.HasMorePages
property is used to indicate a form feed is desired.
The form feed character is sometimes used in plain text files of source code as a delimiter for a page break, or as marker for sections of code. Some editors, in particular emacs and vi, have built-in commands to page up/down on the form feed character. This convention is predominantly used in Lisp code, and is also seen in C and Python source code. GNU Coding Standards require such form feeds in C. [2]
In Usenet, the form feed character is used by several newsreaders as a "spoiler character", causing them to automatically hide the following text until prompted, as a way to prevent spoilers from being inadvertently revealed. [3] The precise behavior depends on the client displaying the article: for example, Gnus displays "Next page..." in boldface, and switches to a second screen to display text after the form feed; slrn displays all non-space characters following the form feed as asterisks; Dialog turns the font and background color red between form feeds; and XRN simply inserts blank lines to fill up the remainder of the article display area so the user must scroll down to reveal the spoiler. This use of the form feed character is not supported by all newsreaders, and is not standardized, although it has appeared in a draft of a Usenet Best Practices document by the IETF's USEFOR working group, as a feature that user agents should (but are not required to) support. [4]
This article needs additional citations for
verification. (May 2013) |
A page break is a marker in an electronic document that tells the document interpreter that the content which follows is part of a new page. A page break causes a form feed to be sent to the printer during spooling of the document to the printer. Thus it is one of the elements that contributes to pagination.
Form feed is a page-breaking
ASCII
control character. It directs the
printer to eject the current
page and to continue printing at the top of another. Often, it will also cause a
carriage return. The form feed character code is defined as 12 (0xC in
hexadecimal), and may be represented as Ctrl+L or ^L. In a related use, Ctrl+L can be used to clear the screen in Unix shells such as
bash, or redraw screen in TUI programs like vi/emacs. In the
C programming language (and other languages derived from C), the form feed character is represented as
'\f'
.
Unicode also provides the character U+21A1 ↡ DOWNWARDS TWO HEADED ARROW as a printable symbol for a form feed (not as the form feed itself).
[1]
The form feed character is considered
whitespace by the
C character classification function isspace()
.
Form feed is seldom used when programming with modern printers in modern operating environments like
Windows,
Unix,
Linux or
macOS. Instead, form feeds are generated by having the printing program call a form feed
API function. For example, when printing using the
.NET Framework, the
PrintPageEventArgs.HasMorePages
property is used to indicate a form feed is desired.
The form feed character is sometimes used in plain text files of source code as a delimiter for a page break, or as marker for sections of code. Some editors, in particular emacs and vi, have built-in commands to page up/down on the form feed character. This convention is predominantly used in Lisp code, and is also seen in C and Python source code. GNU Coding Standards require such form feeds in C. [2]
In Usenet, the form feed character is used by several newsreaders as a "spoiler character", causing them to automatically hide the following text until prompted, as a way to prevent spoilers from being inadvertently revealed. [3] The precise behavior depends on the client displaying the article: for example, Gnus displays "Next page..." in boldface, and switches to a second screen to display text after the form feed; slrn displays all non-space characters following the form feed as asterisks; Dialog turns the font and background color red between form feeds; and XRN simply inserts blank lines to fill up the remainder of the article display area so the user must scroll down to reveal the spoiler. This use of the form feed character is not supported by all newsreaders, and is not standardized, although it has appeared in a draft of a Usenet Best Practices document by the IETF's USEFOR working group, as a feature that user agents should (but are not required to) support. [4]