\fR tags in the HTML output\. For example, this input:
.
.IP "" 4
.
.nf
* Bird
* Magic
.
.fi
.
.IP "" 0
.
.P
will turn into:
.
.IP "" 4
.
.nf
.
.fi
.
.IP "" 0
.
.P
It\'s worth noting that it\'s possible to trigger an ordered list by accident, by writing something like this:
.
.IP "" 4
.
.nf
1986\. What a great season\.
.
.fi
.
.IP "" 0
.
.P
In other words, a \fInumber\-period\-space\fR sequence at the beginning of a line\. To avoid this, you can backslash\-escape the period:
.
.IP "" 4
.
.nf
1986\e\. What a great season\.
.
.fi
.
.IP "" 0
.
.SS "Code Blocks"
Pre\-formatted code blocks are used for writing about programming or markup source code\. Rather than forming normal paragraphs, the lines of a code block are interpreted literally\. Markdown wraps a code block in both \fB\fR and \fB\fR tags\.
.
.P
To produce a code block in Markdown, simply indent every line of the block by at least 4 spaces or 1 tab\. For example, given this input:
.
.IP "" 4
.
.nf
This is a normal paragraph:
This is a code block\.
.
.fi
.
.IP "" 0
.
.P
Markdown will generate:
.
.IP "" 4
.
.nf
This is a normal paragraph:
This is a code block\.
.
.fi
.
.IP "" 0
.
.P
One level of indentation \-\- 4 spaces or 1 tab \-\- is removed from each line of the code block\. For example, this:
.
.IP "" 4
.
.nf
Here is an example of AppleScript:
tell application "Foo"
beep
end tell
.
.fi
.
.IP "" 0
.
.P
will turn into:
.
.IP "" 4
.
.nf
Here is an example of AppleScript:
tell application "Foo"
beep
end tell
.
.fi
.
.IP "" 0
.
.P
A code block continues until it reaches a line that is not indented (or the end of the article)\.
.
.P
Within a code block, ampersands (\fB&\fR) and angle brackets (\fB<\fR and \fB>\fR) are automatically converted into HTML entities\. This makes it very easy to include example HTML source code using Markdown \-\- just paste it and indent it, and Markdown will handle the hassle of encoding the ampersands and angle brackets\. For example, this:
.
.IP "" 4
.
.nf
.
.fi
.
.IP "" 0
.
.P
will turn into:
.
.IP "" 4
.
.nf
<div class="footer">
© 2004 Foo Corporation
</div>
.
.fi
.
.IP "" 0
.
.P
Regular Markdown syntax is not processed within code blocks\. E\.g\., asterisks are just literal asterisks within a code block\. This means it\'s also easy to use Markdown to write about Markdown\'s own syntax\.
.
.SS "Horizontal Rules"
You can produce a horizontal rule tag (\fB
\fR) by placing three or more hyphens, asterisks, or underscores on a line by themselves\. If you wish, you may use spaces between the hyphens or asterisks\. Each of the following lines will produce a horizontal rule:
.
.IP "" 4
.
.nf
* * *
***
*****
\- \- \-
\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
.
.fi
.
.IP "" 0
.
.SH "SPAN ELEMENTS"
.
.SS "Links"
Markdown supports two style of links: \fIinline\fR and \fIreference\fR\.
.
.P
In both styles, the link text is delimited by [square brackets]\.
.
.P
To create an inline link, use a set of regular parentheses immediately after the link text\'s closing square bracket\. Inside the parentheses, put the URL where you want the link to point, along with an \fIoptional\fR title for the link, surrounded in quotes\. For example:
.
.IP "" 4
.
.nf
This is [an example](http://example\.com/ "Title") inline link\.
[This link](http://example\.net/) has no title attribute\.
.
.fi
.
.IP "" 0
.
.P
Will produce:
.
.IP "" 4
.
.nf
This is
an example inline link\.
This link has no
title attribute\.
.
.fi
.
.IP "" 0
.
.P
If you\'re referring to a local resource on the same server, you can use relative paths:
.
.IP "" 4
.
.nf
See my [About](/about/) page for details\.
.
.fi
.
.IP "" 0
.
.P
Reference\-style links use a second set of square brackets, inside which you place a label of your choosing to identify the link:
.
.IP "" 4
.
.nf
This is [an example][id] reference\-style link\.
.
.fi
.
.IP "" 0
.
.P
You can optionally use a space to separate the sets of brackets:
.
.IP "" 4
.
.nf
This is [an example] [id] reference\-style link\.
.
.fi
.
.IP "" 0
.
.P
Then, anywhere in the document, you define your link label like this, on a line by itself:
.
.IP "" 4
.
.nf
[id]: http://example\.com/ "Optional Title Here"
.
.fi
.
.IP "" 0
.
.P
That is:
.
.IP "\(bu" 4
Square brackets containing the link identifier (optionally indented from the left margin using up to three spaces);
.
.IP "\(bu" 4
followed by a colon;
.
.IP "\(bu" 4
followed by one or more spaces (or tabs);
.
.IP "\(bu" 4
followed by the URL for the link;
.
.IP "\(bu" 4
optionally followed by a title attribute for the link, enclosed in double or single quotes, or enclosed in parentheses\.
.
.IP "" 0
.
.P
The following three link definitions are equivalent:
.
.IP "" 4
.
.nf
[foo]: http://example\.com/ "Optional Title Here"
[foo]: http://example\.com/ \'Optional Title Here\'
[foo]: http://example\.com/ (Optional Title Here)
.
.fi
.
.IP "" 0
.
.P
\fBNote:\fR There is a known bug in Markdown\.pl 1\.0\.1 which prevents single quotes from being used to delimit link titles\.
.
.P
The link URL may, optionally, be surrounded by angle brackets:
.
.IP "" 4
.
.nf
[id]: "Optional Title Here"
.
.fi
.
.IP "" 0
.
.P
You can put the title attribute on the next line and use extra spaces or tabs for padding, which tends to look better with longer URLs:
.
.IP "" 4
.
.nf
[id]: http://example\.com/longish/path/to/resource/here
"Optional Title Here"
.
.fi
.
.IP "" 0
.
.P
Link definitions are only used for creating links during Markdown processing, and are stripped from your document in the HTML output\.
.
.P
Link definition names may consist of letters, numbers, spaces, and punctuation \-\- but they are \fInot\fR case sensitive\. E\.g\. these two links:
.
.IP "" 4
.
.nf
[link text][a]
[link text][A]
.
.fi
.
.IP "" 0
.
.P
are equivalent\.
.
.P
The \fIimplicit link name\fR shortcut allows you to omit the name of the link, in which case the link text itself is used as the name\. Just use an empty set of square brackets \-\- e\.g\., to link the word "Google" to the google\.com web site, you could simply write:
.
.IP "" 4
.
.nf
[Google][]
.
.fi
.
.IP "" 0
.
.P
And then define the link:
.
.IP "" 4
.
.nf
[Google]: http://google\.com/
.
.fi
.
.IP "" 0
.
.P
Because link names may contain spaces, this shortcut even works for multiple words in the link text:
.
.IP "" 4
.
.nf
Visit [Daring Fireball][] for more information\.
.
.fi
.
.IP "" 0
.
.P
And then define the link:
.
.IP "" 4
.
.nf
[Daring Fireball]: http://daringfireball\.net/
.
.fi
.
.IP "" 0
.
.P
Link definitions can be placed anywhere in your Markdown document\. I tend to put them immediately after each paragraph in which they\'re used, but if you want, you can put them all at the end of your document, sort of like footnotes\.
.
.P
Here\'s an example of reference links in action:
.
.IP "" 4
.
.nf
I get 10 times more traffic from [Google] [1] than from
[Yahoo] [2] or [MSN] [3]\.
[1]: http://google\.com/ "Google"
[2]: http://search\.yahoo\.com/ "Yahoo Search"
[3]: http://search\.msn\.com/ "MSN Search"
.
.fi
.
.IP "" 0
.
.P
Using the implicit link name shortcut, you could instead write:
.
.IP "" 4
.
.nf
I get 10 times more traffic from [Google][] than from
[Yahoo][] or [MSN][]\.
[google]: http://google\.com/ "Google"
[yahoo]: http://search\.yahoo\.com/ "Yahoo Search"
[msn]: http://search\.msn\.com/ "MSN Search"
.
.fi
.
.IP "" 0
.
.P
Both of the above examples will produce the following HTML output:
.
.IP "" 4
.
.nf
I get 10 times more traffic from Google than from
Yahoo
or MSN\.
.
.fi
.
.IP "" 0
.
.P
For comparison, here is the same paragraph written using Markdown\'s inline link style:
.
.IP "" 4
.
.nf
I get 10 times more traffic from [Google](http://google\.com/ "Google")
than from [Yahoo](http://search\.yahoo\.com/ "Yahoo Search") or
[MSN](http://search\.msn\.com/ "MSN Search")\.
.
.fi
.
.IP "" 0
.
.P
The point of reference\-style links is not that they\'re easier to write\. The point is that with reference\-style links, your document source is vastly more readable\. Compare the above examples: using reference\-style links, the paragraph itself is only 81 characters long; with inline\-style links, it\'s 176 characters; and as raw HTML, it\'s 234 characters\. In the raw HTML, there\'s more markup than there is text\.
.
.P
With Markdown\'s reference\-style links, a source document much more closely resembles the final output, as rendered in a browser\. By allowing you to move the markup\-related metadata out of the paragraph, you can add links without interrupting the narrative flow of your prose\.
.
.SS "Emphasis"
Markdown treats asterisks (\fB*\fR) and underscores (\fB_\fR) as indicators of emphasis\. Text wrapped with one \fB*\fR or \fB_\fR will be wrapped with an HTML \fB\fR tag; double \fB*\fR\'s or \fB_\fR\'s will be wrapped with an HTML \fB\fR tag\. E\.g\., this input:
.
.IP "" 4
.
.nf
*single asterisks*
_single underscores_
**double asterisks**
__double underscores__
.
.fi
.
.IP "" 0
.
.P
will produce:
.
.IP "" 4
.
.nf
single asterisks
single underscores
double asterisks
double underscores
.
.fi
.
.IP "" 0
.
.P
You can use whichever style you prefer; the lone restriction is that the same character must be used to open and close an emphasis span\.
.
.P
Emphasis can be used in the middle of a word:
.
.IP "" 4
.
.nf
un*frigging*believable
.
.fi
.
.IP "" 0
.
.P
But if you surround an \fB*\fR or \fB_\fR with spaces, it\'ll be treated as a literal asterisk or underscore\.
.
.P
To produce a literal asterisk or underscore at a position where it would otherwise be used as an emphasis delimiter, you can backslash escape it:
.
.IP "" 4
.
.nf
\e*this text is surrounded by literal asterisks\e*
.
.fi
.
.IP "" 0
.
.SS "Code"
To indicate a span of code, wrap it with backtick quotes (\fB`\fR)\. Unlike a pre\-formatted code block, a code span indicates code within a normal paragraph\. For example:
.
.IP "" 4
.
.nf
Use the `printf()` function\.
.
.fi
.
.IP "" 0
.
.P
will produce:
.
.IP "" 4
.
.nf
Use the printf()
function\.
.
.fi
.
.IP "" 0
.
.P
To include a literal backtick character within a code span, you can use multiple backticks as the opening and closing delimiters:
.
.IP "" 4
.
.nf
``There is a literal backtick (`) here\.``
.
.fi
.
.IP "" 0
.
.P
which will produce this:
.
.IP "" 4
.
.nf
There is a literal backtick (`) here\.
.
.fi
.
.IP "" 0
.
.P
The backtick delimiters surrounding a code span may include spaces \-\- one after the opening, one before the closing\. This allows you to place literal backtick characters at the beginning or end of a code span:
.
.IP "" 4
.
.nf
A single backtick in a code span: `` ` ``
A backtick\-delimited string in a code span: `` `foo` ``
.
.fi
.
.IP "" 0
.
.P
will produce:
.
.IP "" 4
.
.nf
A single backtick in a code span: `
A backtick\-delimited string in a code span: `foo`
.
.fi
.
.IP "" 0
.
.P
With a code span, ampersands and angle brackets are encoded as HTML entities automatically, which makes it easy to include example HTML tags\. Markdown will turn this:
.
.IP "" 4
.
.nf
Please don\'t use any `