9. Text

The following sections discuss issues surrounding the structuring of text.Elements that present text (alignmentelements, font elements, style sheets, etc.) are discussed elsewhere in thespecification. For information about characters, please consult the section onthe document character set.

9.1 White space

The document character set includes a widevariety of white space characters. Many of these are typographic elements usedin some applications to produce particular visual spacing effects. In HTML,only the following characters are defined as white spacecharacters:

• ASCII space ( )
• ASCII tab (	)
• ASCII form feed ()
• Zero-width space (​)

Line breaks are also white space characters. Notethat although 
 and 
 are defined in [ISO10646] tounambiguously separate lines and paragraphs, respectively, these do notconstitute line breaks in HTML, nor does this specification include them in themore general category of white space characters.

This specification does not indicate the behavior, rendering or otherwise,of space characters other than those explicitly identified here as white spacecharacters. For this reason, authors should use appropriate elements and stylesto achieve visual formatting effects that involve white space, rather thanspace characters.

For all HTML elements except PRE, sequences of white space separate "words"(we use the term "word" here to mean "sequences of non-white spacecharacters"). When formatting text, user agents should identify these words andlay them out according to the conventions of the particular written language(script) and target medium.

This layout may involve putting space between words (called inter-word space), but conventions for inter-word space varyfrom script to script. For example, in Latin scripts, inter-word space istypically rendered as an ASCII space ( ), while in Thai it is azero-width word separator (​). In Japanese and Chinese, inter-wordspace is not typically rendered at all.

Note that a sequence of white spaces between words in the source documentmay result in an entirely different rendered inter-word spacing (except in thecase of the PRE element). In particular, user agents should collapse input white space sequences when producing outputinter-word space. This can and should be done even in the absence of languageinformation (from the lang attribute, the HTTP "Content-Language" header field (see [RFC2616], section14.12), user agent settings, etc.).

The PRE element is used for preformattedtext, where white space is significant.

In order to avoid problems with SGML line break rules andinconsistencies among extant implementations, authors should not rely on useragents to render white space immediately after a start tag or immediatelybefore an end tag. Thus, authors, and in particular authoring tools,should write:

  <P>We offer free <A>technical support</A> for subscribers.</P>

and not:

  <P>We offer free<A> technical support </A>for subscribers.</P>

9.2 Structured text

9.2.1 Phrase elements: EM, STRONG, DFN, CODE, SAMP, KBD, VAR, CITE, ABBR, and ACRONYM

<!ENTITY % phrase "EM | STRONG | DFN | CODE |   SAMP | KBD | VAR | CITE | ABBR | ACRONYM" ><!ELEMENT (%fontstyle;|%phrase;) - - (%inline;)*><!ATTLIST (%fontstyle;|%phrase;)  %attrs;  -- %coreattrs, %i18n, %events --  >

Start tag: required, End tag: required

Phrase elements add structural information to text fragments. The usualmeanings of phrase elements are following:

EM:

Indicates emphasis.

STRONG:

Indicates stronger emphasis.

CITE:

Contains a citation or a reference to other sources.

DFN:

Indicates that this is the defining instance of the enclosed term.

CODE:

Designates a fragment of computer code.

SAMP:

Designates sample output from programs, scripts, etc.

KBD:

Indicates text to be entered by the user.

VAR:

Indicates an instance of a variable or program argument.

ABBR:

Indicates an abbreviated form (e.g., WWW, HTTP, URI, Mass., etc.).

ACRONYM:

Indicates an acronym (e.g., WAC, radar, etc.).

EMand STRONG are used to indicate emphasis. The other phrase elements haveparticular significance in technical documents. These examples illustrate someof the phrase elements:

As <CITE>Harry S. Truman</CITE> said,<Q lang="en-us">The buck stops here.</Q>More information can be found in <CITE>[ISO-0000]</CITE>.Please refer to the following reference number in futurecorrespondence: <STRONG>1-234-55</STRONG>

The presentation of phrase elements depends on the user agent. Generally,visual user agents present EM text in italics and STRONG text in bold font. Speechsynthesizer user agents may change the synthesis parameters, such as volume,pitch and rate accordingly.

The ABBR and ACRONYM elements allow authors to clearly indicateoccurrences of abbreviations and acronyms.Western languages make extensive use of acronyms such as "GmbH", "NATO", and"F.B.I.", as well as abbreviations like "M.", "Inc.", "et al.", "etc.". BothChinese and Japanese use analogous abbreviation mechanisms, wherein a long nameis referred to subsequently with a subset of the Han characters from theoriginal occurrence. Marking up these constructs provides useful information touser agents and tools such as spell checkers, speech synthesizers, translationsystems and search-engine indexers.

The content of the ABBR and ACRONYM elements specifies the abbreviatedexpression itself, as it would normally appear in running text. The titleattribute of these elements may be used to provide the full or expanded form ofthe expression.

  <P>  <ABBR title="World Wide Web">WWW</ABBR>  <ABBR lang="fr" title="Soci&eacute;t&eacute; Nationale des Chemins de Fer"> SNCF  </ABBR>  <ABBR lang="es" title="Do&ntilde;a">Do&ntilde;a</ABBR>  <ABBR title="Abbreviation">abbr.</ABBR>

Note that abbreviations and acronyms often have idiosyncraticpronunciations. For example, while "IRS" and "BBC" are typically pronouncedletter by letter, "NATO" and "UNESCO" are pronounced phonetically. Still otherabbreviated forms (e.g., "URI" and "SQL") are spelled out by some people andpronounced as words by other people. When necessary, authors should use stylesheets to specify the pronunciation of an abbreviated form.

9.2.2 Quotations: The BLOCKQUOTE and Q elements

<!ELEMENT BLOCKQUOTE - - (%block;|SCRIPT)+ -- long quotation --><!ATTLIST BLOCKQUOTE  %attrs;  -- %coreattrs, %i18n, %events --  cite %URI;  #IMPLIED  -- URI for source document or msg --  ><!ELEMENT Q - - (%inline;)* -- short inline quotation --><!ATTLIST Q  %attrs;  -- %coreattrs, %i18n, %events --  cite %URI;  #IMPLIED  -- URI for source document or msg --  >

Start tag: required, End tag: required

These two elements designate quoted text. BLOCKQUOTE is for long quotations (block-level content) and Q is intendedfor short quotations (inline content) that don't require paragraph breaks.

<BLOCKQUOTE cite="http://www.mycom.com/tolkien/twotowers.html"><P>They went in single file, running like hounds on a strong scent,and an eager light was in their eyes. Nearly due west the broadswath of the marching Orcs tramped its ugly slot; the sweet grassof Rohan had been bruised and blackened as they passed.</P></BLOCKQUOTE>

Rendering quotations 

Visual user agents generally render BLOCKQUOTE as an indentedblock.

Visual user agents must ensure that the content of the Q element isrendered with delimiting quotation marks. Authors should not put quotationmarks at the beginning and end of the content of a Q element.

User agents should render quotation marks in a language-sensitive manner(see the lang attribute). Many languages adopt different quotation styles forouter and inner (nested) quotations, which should be respected byuser-agents.

John said, <Q lang="en-us">I saw Lucy at lunch, she told me<Q lang="en-us">Mary wants youto get some ice cream on your way home.</Q> I think I will getsome at Ben and Jerry's, on Gloucester Road.</Q>

  John said, "I saw Lucy at lunch, she told me 'Mary wants you  to get some ice cream on your way home.' I think I will get some  at Ben and Jerry's, on Gloucester Road."

9.2.3 Subscripts and superscripts: the SUB and SUP elements

<!ELEMENT (SUB|SUP) - - (%inline;)* -- subscript, superscript --><!ATTLIST (SUB|SUP)  %attrs;  -- %coreattrs, %i18n, %events --  >

Start tag: required, End tag: required

Many scripts (e.g., French) require superscripts or subscripts for properrendering. The SUB and SUP elements should be used to markup text in thesecases.

  H<sub>2</sub>O  E = mc<sup>2</sup>  <SPAN lang="fr">M<sup>lle</sup> Dupont</SPAN>

9.3 Lines and Paragraphs

Authors traditionally divide their thoughts and arguments into sequences ofparagraphs. The organization of information into paragraphs is not affected byhow the paragraphs are presented: paragraphs that are double-justified containthe same thoughts as those that are left-justified.

The HTML markup for defining a paragraph is straightforward: the P elementdefines a paragraph.

The visual presentation of paragraphs is not so simple. A number of issues,both stylistic and technical, must be addressed:

• Treatment of white space
• Line breaking and word wrapping
• Justification
• Hyphenation
• Written language conventions and text directionality
• Formatting of paragraphs with respect to surrounding content

We address these questions below. Paragraph alignment and floatingobjects are discussed later in this document.

9.3.1 Paragraphs: the P element

<!ELEMENT P - O (%inline;)* -- paragraph --><!ATTLIST P  %attrs;  -- %coreattrs, %i18n, %events --  >

Start tag: required, End tag: optional

The P element represents a paragraph. It cannot contain block-level elements (including P itself).

We discourage authors from using empty P elements. User agents should ignoreempty P elements.

9.3.2 Controlling linebreaks

A line break is defined to be a carriage return (
),a line feed (
), or a carriage return/line feed pair. All linebreaks constitute white space.

For more information about SGML's specification of line breaks, pleaseconsult the notes on linebreaks in the appendix.

Forcing a line break: the BR element 

<!ELEMENT BR - O EMPTY -- forced line break --><!ATTLIST BR  %coreattrs;  -- id, class, style, title --  >

Start tag: required, End tag: forbidden

The BR element forcibly breaks (ends) the current line of text.

For visual user agents, the clear attribute can be used todetermine whether markup following the BR element flows around images andother objects floated to the left or right margin, or whether it starts afterthe bottom of such objects. Further details are given in the section on alignment and floating objects.Authors are advised to use style sheets to control text flow around floatingimages and other objects.

With respect to bidirectionalformatting, the BR element should behave the same way the [ISO10646] LINE SEPARATOR character behaves in the bidirectionalalgorithm.

Prohibiting a line break 

Sometimes authors may want to prevent a line break from occurring betweentwo words. The   entity (  or  ) acts as a spacewhere user agents should not cause a line break.

9.3.3 Hyphenation

In HTML, there are two types of hyphens: the plain hyphen and the softhyphen. The plain hyphen should be interpreted by a user agent as just anothercharacter. The soft hyphen tells the user agent where a linebreak can occur.

Those browsers that interpret soft hyphens must observe the followingsemantics: If a line is broken at a soft hyphen, a hyphen character must bedisplayed at the end of the first line. If a line is not broken at a softhyphen, the user agent must not display a hyphen character. For operations suchas searching and sorting, the soft hyphen should always be ignored.

In HTML, the plain hyphen is represented by the "-" character (- or-). The soft hyphen is represented by the character entity reference­ (­ or ­)

9.3.4 Preformatted text:The PRE element

<!ENTITY % pre.exclusion "IMG|OBJECT|BIG|SMALL|SUB|SUP"><!ELEMENT PRE - - (%inline;)* -(%pre.exclusion;) -- preformatted text --><!ATTLIST PRE  %attrs;  -- %coreattrs, %i18n, %events --  >

Start tag: required, End tag: required

The PRE element tells visual user agents that the enclosed text is "preformatted". When handling preformatted text,visual user agents:

• May leave white space intact.
• May render text with a fixed-pitch font.
• May disable automatic word wrap.
• Must not disable bidirectional processing.

Non-visual user agents are not required to respect extra white space in the content of a PRE element.

For more information about SGML's specification of line breaks, pleaseconsult the notes on linebreaks in the appendix.

The DTD fragment above indicates which elements may not appear within a PREdeclaration. This is the same as in HTML 3.2, and is intended to preserveconstant line spacing and column alignment for text rendered in a fixed pitchfont. Authors are discouraged from altering this behavior through stylesheets.

<PRE>   Higher still and higher From the earth thou springest   Like a cloud of fire; The blue deep thou wingest,And singing still dost soar, and soaring ever singest.</PRE>

   Higher still and higher From the earth thou springest   Like a cloud of fire; The blue deep thou wingest,And singing still dost soar, and soaring ever singest.

9.3.5 Visual rendering ofparagraphs

How paragraphs are rendered visually depends on the user agent. Paragraphsare usually rendered flush left with a ragged right margin. Other defaults areappropriate for right-to-left scripts.

HTML user agents have traditionally rendered paragraphs with white spacebefore and after, e.g.,

  At the same time, there began to take form a system of numbering,  the calendar, hieroglyphic writing, and a technically advanced  art, all of which later influenced other peoples.  Within the framework of this gradual evolution or cultural  progress the Preclassic horizon has been divided into Lower,  Middle and Upper periods, to which can be added a transitional  or Protoclassic period with several features that would later  distinguish the emerging civilizations of Mesoamerica.

This contrasts with the style used in novels which indents the first line ofthe paragraph and uses the regular line spacing between the final line of thecurrent paragraph and the first line of the next, e.g.,

 At the same time, there began to take form a system of  numbering, the calendar, hieroglyphic writing, and a technically  advanced art, all of which later influenced other peoples. Within the framework of this gradual evolution or cultural  progress the Preclassic horizon has been divided into Lower,  Middle and Upper periods, to which can be added a transitional  or Protoclassic period with several features that would later  distinguish the emerging civilizations of Mesoamerica.

Following the precedent set by the NCSA Mosaic browser in 1993, user agentsgenerally don't justify both margins, in part because it's hard to do thiseffectively without sophisticated hyphenation routines. The advent of stylesheets, and anti-aliased fonts with subpixel positioning promises to offerricher choices to HTML authors than previously possible.

Style sheets provide rich control over the size and style of a font, themargins, space before and after a paragraph, the first line indent,justification and many other details. The user agent's default style sheetrenders P elements in a familiar form, as illustrated above. One could, inprinciple, override this to render paragraphs without the breaks thatconventionally distinguish successive paragraphs. In general, since this mayconfuse readers, we discourage this practice.

By convention, visual HTML user agents wrap textlines to fit within the available margins. Wrapping algorithmsdepend on the script being formatted.

In Western scripts, for example, text should only be wrapped at white space.Early user agents incorrectly wrapped lines just after the start tag or justbefore the end tag of an element, which resulted in dangling punctuation. Forexample, consider this sentence:

   A statue of the <A href="cih78">Cihuateteus</A>, who are patron ...

  A statue of the Cihuateteus  , who are patron ...

9.4 Marking document changes: The INS and DEL elements

<!-- INS/DEL are handled by inclusion on BODY --><!ELEMENT (INS|DEL) - - (%flow;)*  -- inserted text, deleted text --><!ATTLIST (INS|DEL)  %attrs;  -- %coreattrs, %i18n, %events --  cite %URI;  #IMPLIED  -- info on reason for change --  datetime %Datetime; #IMPLIED  -- date and time of change --  >

Start tag: required, End tag: required

INS and DEL are used to markup sections of the document that havebeen inserted or deleted with respect to a differentversion of a document (e.g., in draft legislation where lawmakers need to viewthe changes).

These two elements are unusual for HTML in that they may serve as eitherblock-level or inline elements (but not both). They may contain one or morewords within a paragraph or contain one or more block-level elements such asparagraphs, lists and tables.

<P>  A Sheriff can employ <DEL>3</DEL><INS>5</INS> deputies.</P>

The INS and DEL elements must not contain block-level content when theseelements behave as inline elements.

<P><INS><DIV>...block-level content...</DIV></INS></P>

User agents should render inserted and deleted text in ways that make thechange obvious. For instance, inserted text may appear in a special font,deleted text may not be shown at all or be shown as struck-through or withspecial markings, etc.

 1994-11-05T13:15:30Z 1994-11-05T08:15:30-05:00

<INS datetime="1994-11-05T08:15:30-05:00" cite="http://www.foo.org/mydoc/comments.html">Furthermore, the latest figures from the marketing departmentsuggest that such practice is on the rise.</INS>

Authors may also make comments about inserted or deleted text by means ofthe title attribute for the INS and DEL elements. User agents may presentthis information to the user (e.g., as a popup note). For example:

<INS datetime="1994-11-05T08:15:30-05:00" title="Changed as a result of Steve B's comments in meeting.">Furthermore, the latest figures from the marketing departmentsuggest that such practice is on the rise.</INS>