RISC DISC 2/RISC_DISC_2.iso/the_web/documents/spec/html_spec/blocks_sgm

Text File | 1995-06-15 | 5.2 KB | 154 lines

<!-- $Id: blocks.sgm,v 1.9 1995/06/15 20:16:38 connolly Exp $ -->
<h2>Block Structuring Elements

<p>Block structuring elements include paragraphs, lists, and block
quotes. They must not contain heading elements, but they may contain
phrase markup, and in some cases, they may be nested.

<h3>Paragraph: P

<p>The <tag/P/ element indicates a paragraph. The exact indentation,
leading space, etc. of a paragraph is not specified and may be a
function of other tags, style sheets, etc.

<p>Typically, paragraphs are surrounded by a vertical space of one
line or half a line. The first line in a paragraph is indented in some
cases.

<p>Example of use:

<listing><![CDATA[
<H1>This Heading Precedes the Paragraph</H1>
<P>This is the text of the first paragraph.
<P>This is the text of the second paragraph. Although you do not
need to start paragraphs on new lines, maintaining this
convention facilitates document maintenance.</P>
<P>This is the text of a third paragraph.</P>
]]></listing>

<h3 id=pre>Preformatted Text: PRE

<p>The <tag/PRE/ element represents a character cell block of text and
is suitable for text that has been formatted for a monospaced font.

<p>The <tag/PRE/ tag may be used with the optional <attr/WIDTH/
attribute. The WIDTH attribute specifies the maximum number of
characters for a line and allows the HTML user agent to select a
suitable font and indentation.

<p>Within preformatted text:

<ul>
<li>Line breaks within the text are rendered as a move to the
beginning of the next line.
<NOTE>References to the "beginning of a new line" do not imply that
the renderer is forbidden from using a constant left indent for
rendering preformatted text. The left indent may be constrained by the
width required.
</note>

<li>Anchor elements and phrase markup may be used.
<NOTE>Constraints on the processing of <tag/PRE/ content may may limit or
prevent the ability of the HTML user agent to faithfully render
phrase markup.
</note>

<li>Elements that define paragraph formatting (headings, address,
etc.) must not be used.
<NOTE>Some historical documents contain <tag/P/ tags in <tag/PRE/
elements.  User agents are encouraged to treat this as a line break. A
<tag/P/ tag followed by a newline character should produce only one
line break, not a line break plus a blank line.
</note>

<li>The horizontal tab character (code position 9 in the HTML document
character set) must be interpreted as the smallest positive nonzero
number of spaces which will leave the number of characters so far on
the line as a multiple of 8. Documents should not contain tab
characters, as they are not supported consistently.
</ul>

<p>Example of use:

<listing><![CDATA[
<PRE>
Line 1.
       Line 2 is to the right of line 1.     <a href="abc">abc</a>
       Line 3 aligns with line 2.            <a href="def">def</a>
</PRE>
]]></listing>

<h4 id=xmp>Example and Listing: XMP, LISTING

<p>The <tag/XMP/ and <tag/LISTING/ elements are similar to the
<tag/PRE/ element, but they have a different syntax. Their content is
declared as CDATA, which means that no markup except the end-tag open
delimiter-in-context is recognized (see 9.6 "Delimiter Recognition" of
[SGML]).
<note>In a previous draft of the HTML specification, the syntax
of <tag/XMP/ and <tag/LISTING/ elements allowed closing tags to
be treated as data characters, as long as the tag name was not
<tag/XMP/ or <tag/LISTING/, respectively.
</note>

<p>Since CDATA declared content has a number of unfortunate
interactions with processing techniques and tends to be used and
implemented inconsistently, HTML documents should not contain
<tag/XMP/ nor <tag/LISTING/ elements — the <tag/PRE/ tag is more
expressive and more consistently supported.

<p>The <tag/LISTING/ element should be rendered so that at least 132
characters fit on a line. The <tag/XMP/ element should be rendered so
that at least 80 characters fit on a line but is otherwise identical
to the <tag/LISTING/ element.
<note>
In a previous draft, HTML included a <tag/PLAINTEXT/ element that
is similar to the <tag/LISTING/ element, except that there is
no closing tag: all characters after the <tag/PLAINTEXT/ start-tag
are data.
</note>

<h3>Address: ADDRESS

<p>The <tag/ADDRESS/ element contains such information as address,
signature and authorship, often at the beginning or end of the body of
a document.

<p>Typically, the <tag/ADDRESS/ element is rendered in an italic
typeface and may be indented.

<p>Example of use:

<listing><![CDATA[
<ADDRESS>
Newsletter editor<BR>
J.R. Brown<BR>
JimquickPost News, Jimquick, CT 01234<BR>
Tel [phone]
</ADDRESS>
]]></listing>

<h3>Block Quote: BLOCKQUOTE

<p>The <tag/BLOCKQUOTE/ element contains text quoted from another
source.

<p>A typical rendering might be a slight extra left and right indent,
and/or italic font. The <tag/BLOCKQUOTE/ typically provides space
above and below the quote.

<p>Single-font rendition may reflect the quotation style of Internet
mail by putting a vertical line of graphic characters, such as the
greater than symbol (>), in the left margin.

<p>Example of use:

<listing><![CDATA[
I think the poem ends
<BLOCKQUOTE>
<P>Soft you now, the fair Ophelia. Nymph, in thy orisons, be all
my sins remembered.
</BLOCKQUOTE>
but I am not sure.
]]></listing>