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Apage break is a marker in an electronicdocument that tells the document interpreter 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. It is one of the elements that contributes topagination.
Form feed is a page-breakingASCIIcontrol character. It directs theprinter to eject the currentpage and to continue printing at the top of another. It will often also cause acarriage return. The form feed character code is defined as 12 (0xC inhexadecimal), and may be represented asCtrl+L or^L. In a related use,Ctrl+L can be pressed to clear the screen in Unix shells such asbash, or redraw the screen in TUI programs like vi/emacs. In theC programming language (and other languages derived from C), the form feed character is represented as'\f'.Unicode also provides the characterU+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 consideredwhitespace by theC character classification functionisspace().
Form feed is rarely used when programming with modern printers in modern operating environments such asWindows,Unix,Linux ormacOS. Instead, form feeds are generated by having the printing program call a form feedAPI 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 particularemacs andvi, have built-in commands to page up/down on the form feed character. This convention is predominantly used inLisp code, and is also seen inC andPython source code.GNU Coding Standards require such form feeds in C.[2]
InUsenet, 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 preventspoilers 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 asasterisks; Dialog turns the font and background color red between form feeds; andXRN simply inserts blank lines to fill 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]