Non-breaking space
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In computer-based text processing and digital typesetting, a non-breaking space or no-break space (NBSP) is a variant of the space character that prevents an automatic line break (line wrap) at its position. In certain formats (such as HTML) it also prevents the "collapsing" of multiple consecutive whitespace characters into a single space. The non-breaking space is also known as a hard space or fixed space.
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[edit] Non-breaking behaviour
Text-processing software typically assumes that an automatic line break may be inserted anywhere a space character occurs; a non-breaking space prevents this happening (provided the software recognises the character, of course). For example, if the text "100 km" will not quite fit at the end of a line, the software may insert a line break between "100" and "km". To avoid this undesirable behaviour, the editor may choose to use a non-breaking space between "100" and "km". This guarantees that the text "100 km" will not be broken: if it does not fit at the end of a line it is moved in its entirety to the next line.
Non-breaking spaces may be used between words and punctuation in traditional typesetting's spacing rules. In French spacing, for example, a narrow non-breaking space is inserted between words and their enclosing quotation marks (for first-level quotation marks only) and between the last word of a sentence and a composite punctuation sign (semi-colon, question mark, exclamation mark, interrobang…).
[edit] Use as non-collapsing whitespace
A second common application of non-breaking spaces is in plain text file formats such as SGML, HTML, TeX and LaTeX that treat sequences of whitespace characters (space, newline, tab, form feed, etc.) as if they were a single whitespace character. Such "collapsing" of whitespace allows the author to neatly arrange the source text using line breaks, indentation and other forms of spacing without affecting the final typeset result.
In contrast, non-breaking spaces are not merged with neighboring whitespace characters, and can therefore be used by an author to insert additional visible space in the formatted text. For example, in HTML, non-breaking spaces may be used in conjunction with a fixed-width font to create tabular alignment:
Column 1 Column 2
-------- --------
1.2 2.3
(notice that the use of the pre tag is an alternative, if not better way to achieve the same result)
If ordinary spaces are used instead then the spaces are collapsed when the HTML is rendered and the layout is broken:
Column 1 Column 2
-------- --------
1.2 2.3
[edit] Encodings
| Format | Representation of non-breaking space |
|---|---|
| Unicode and ISO/IEC 10646 | U+00A0. This can be encoded by UTF-8 as 0xC2 0xA0. |
| ISO/IEC 8859 | 0xA0 |
| CP1252 (windows default) | 0xA0 |
| KOI8-R | 0x9A |
| EBCDIC | 0x41 |
| CP437 and CP850 | 0xFF |
| SGML and HTML (including Wikitext) | Character entity reference: Numeric character references:   or   |
| TeX | tilde (~) |
| ASCII | Not available |
Unicode defines several other non-break space characters that differ from the regular space in width:
- No-break thin space, known in Unicode as "NARROW NO-BREAK SPACE" (U+202F). This is required for French punctuation (before ?, ! or ;).
- Word joiner, encoded in Unicode 3.2 and above as U+2060. The word-joiner does not normally produce any space but prohibits a line break on either side of it.
- The Byte Order Mark, U+FEFF, officially named "ZERO WIDTH NO-BREAK SPACE", can also be used with the same meaning as the word joiner, but in current documents this use is deprecated. See also Zero-width non-breaking space.
[edit] Keyboard entry methods
None of the existing national or international standards on keyboard layouts currently define an input method for the non-breaking space. Therefore, authors of keyboard drivers and application programs (e.g., word processors) have devised their own keyboard shortcuts. For example:
| System/application | Entry method |
|---|---|
| Mac OS | Option+Space |
| Microsoft Windows | Alt+0160 (typed on numeric keypad) |
| X11 | Compose, Space, Space |
| emacs | Ctrl+X 8 Space |
| vim | Ctrl+K N S |
| Microsoft Word, Dreamweaver, OpenOffice.org (since 3.0) |
Ctrl+Shift+Space |
| WordPerfect, OpenOffice.org (before 3.0), LyX | Ctrl+Space |
| GNOME | Ctrl+Shift+U 00A0 |
| Many office applications[vague] | Insert → Symbol dialog box (Latin-1 subset, after ~) |
[edit] See also
- Space (punctuation), symbol "Word Joiner"
- Byte_order_mark, formerly known as "zero width no-break space"
- Punctuation
- Hyphens in computing, for information about hard and non-breaking hyphens
- List of XML and HTML character entity references
- Double spacing at the end of sentences – Computer software
