Provided by: lowdown_0.10.0-1_amd64 
NAME
lowdown — Markdown reference for lowdown
DESCRIPTION
Markdown is a simple, plain-text formatting language. “Plain-text” in this case means the document input
looks similar to the output, less the formatting niceties (boxed tables, italics, clickable links, etc.)
provided by the output medium. For example:
# How to be a Picard fan
## Introduction
In order to develop fandom skills one must first and foremost
know *whom* one idolises. Therefore: **who is Captain Picard**?
1. Picard was named the \*Best Star Trek Captain\*, according
to a [5-week poll](poll.html).
> Picard continued his winning ways in the final week,
> with fans naming him the most inspiring captain.
2. Picard is handsome. 
3. Picard knows how to code: `make engage`
---------------------------------
## Picard Fandom
Here's why everyone wants to be a fan...
This example consists of a series of block elements: section header, sub-section header, paragraph, set of
list elements, horizontal rule, then another sub-section header. Each block element contains span
elements: normal text, emphasised text (bold and italised), an image, a link, and a span of code.
This document describes the Markdown syntax accepted by lowdown(1).
BLOCK ELEMENTS
A block element starts on a new line and extends to the next blank line or block element. A block element
contains span elements.
Paragraphs and Line Breaks
A paragraph is made up of one or more lines of text possibly containing span elements. Paragraphs are
separated by blank lines.
To insert a hard line break (i.e., a line-break in the input that is reproduced in the output), insert two
spaces at the end of the line. If commonmark input parsing is enabled, this may also be effected by
escaping the newline:
Darmok and Jalad...\
at Tanagra.
Headers
There are two styles of headers: underlined (“setext”) and hash-marked (“atx”). For underlined headers,
underline the given word using equal signs (“=”) for first-level headers and dashes (“-”) for second-level
headers.
This is an underlined header 1
==============================
For hash-marked headers, use the corresponding number of hash characters to the corresponding level of
header, up to 6 levels, at the start of the line separated by one space followed by the header.
## This is a hash-marked header 2
If commonmark input parsing is enabled, the space is required after the hash-marks in any hash-marked
header.
Block Quotes
Block quoted sections are invoked with a single right-angle bracket (“>”) followed by a space at the start
of each line and between paragraphs.
> The Prime Directive is not just a set of rules;
> it is a philosophy... and a very correct one.
>
> (It goes on for a few paragraphs).
Block quotes may also have a non-multiline invocation: you need only invoke the right-angle bracket at the
start of a paragraph and omit it entirely between paragraphs.
> You cannot explain away a wantonly immoral act because
you think it is connected to some higher purpose.
> Here is another paragraph about Picard wisdom.
Consecutive blockquotes as above will be merged as paragraphs within a single block quote on output, even
if styles (non-multiline and otherwise) are mixed.
Block quotes may be nested within other block quotes, as may any other block elements such as headers,
ordered/unordered lists, and code blocks.
> ### hash-marked header 3
>
> > I'd be delighted to offer any advice
> > I have on understanding women.
> > When I have some, I'll let you know.
>
> 1. advice list item 1
> 2. advice list item 2
>
> Here's the code to implement JLP's advice:
> yes | read engage
Lists
Lists may be specified as ordered (numbered) or unordered. Ordered lists are invoked as numbers followed
by periods (e.g., “1.”) and rendered in a similar format. Note: it does not matter which order or which
numbers you use in your ordered lists, as all ordered lists start at one.
1. Make.
2. It.
1. So. (Not 1. again!)
If commonmark input parsing is enabled, list items may alternatively terminate with the right parenthesis:
1) Live long
2) Prosper
To prevent lists erroneously started by a paragraph beginning with a number and period, use a backslash
before the period.
1987. The year TNG premiered.
1987\. The year TNG premiered.
Unordered lists, on the other hand, can be invoked using either asterisk (“*”), pluses (“+”), or hyphens
(“-”), and can be a mix of all three styles. Regardless the style, list items are rendered the same way.
- Earl Grey tea.
* Shakespeare.
+ Exotic fish.
All nested block elements need a new line break, otherwise they will be rendered on the same line as the
list item on output. To insert paragraphs into a list item, indent each paragraph with either four spaces
or one tab.
- First list item
Courage can be an emotion too.
Things are only impossible until they're not.
+ Second list item
+ Third list item
To insert block quotes into a list item, indent the block quote with four spaces or one tab prior to the
right-angle bracket (“>”).
* List item 1
* List item 2
> I am Locutus of Borg.
> That is the cutest of Borg.
Code blocks need to be indented twice (two tabs or eight leading spaces): once for being recognised within
the list item, another for the code block itself.
* Here is a list item for an indented code block:
alias path='echo -e ${PATH//:/\n}'
To make list elements occur in tight sequence — like a grocery list — don't have an empty line between the
items.
- Phaser
- Communicator
On the other hand, if you want to render lists separated by white-space, use the following syntax:
- A phaser is a type of weapon.
- A communicator keeps Riker in contact with Troi.
This applies to ordered and unordered list types.
Task lists
One form of an unordered list is task lists, a GFM extension. These begin with checkboxes (checked or
not), rendered similarly in the output.
Star Trek series with episodes in the Delta quadrant:
- [ ] Original series
- [x] TNG
- [ ] DS9
- [x] Voyager
- [ ] Enterprise
- [ ] Discovery
The check may be upper or lower case. A space must follow the right square bracket.
Definition Lists
Definition lists are a PHP Extra extension. They're similar to lists except in having key and value pairs,
with keys being preceded by a blank line:
Best understated characters:
*Quark*
: Armin Shimerman
*Weyoun*
: Jeffrey Combs
Keys consist of a single line and may contain inline elements. Like other lists, values may consist of
arbitrary nested blocks. There may be multiple consecutive values per key. If the key and value are
separated by a blank line, the list is emitted as if it contained block elements (usually output as spacing
between key-value pairs).
Code Blocks
Code blocks consist of pre-formatted text, such as source code. Each code block contains opaque/literal
text. This means that new lines and white spaces are retained — they're not formatted in any way, and any
text inside the code block is not interpreted. To invoke a code block, create a line break then indent
each line with four spaces or one tab.
Here is a paragraph about Bridge protocol
Here is a code block for the command "Engage"
Within a code block, text is escaped given the output format. Therefore, characters that would normally
need to be escaped in other text processing languages such as ampersands (“&”) do not need to be escaped.
Here is how you start the program xterm:
xterm &
Horizontal Rules
A horizontal rule is a line that goes across an output page. These are invoked with three or more
asterisks (“*”), hyphens (“-”), or underscores (“_”) on their own line. Spaces between these characters
are disregarded.
***
* * *
---
- - -
___
_ _ _
___________________________
Metadata
Documents can include metadata that is not part of the main text. The syntax loosely follows the
"Multimarkdown" specification.
The metadata block begins on the document's first line and continues until the first blank line. It
consists of one or more key-value pairs, with keys and values separated by a colon, and pairs separated by
a newline. A key (and following value) must exist on the line beginning the metadata pair, but the value
may span multiple lines.
Title: Captain's log
Author: Captain J-L Picard
Summary: As part of an exchange program, we're taking
aboard a Klingon officer to return the recent visit
of Commander Riker to the cruiser Pagh.
Stardate: 43917.4
If there are multiple lines of text in a metadata value, subsequent lines should (but need not) be offset
with whitespace. Otherwise, they must not have a colon in the value, else they will be construed as a
subsequent pair's key.
End each line with two spaces to ensure linebreaks are rendered on output for non-conforming Markdown
renderers. Moreover, beginning a document with a regular sentence containing a colon might invoke
metadata. To escape this, add one blank line to the beginning of the document.
Metadata keys must consist of alphanumeric ASCII characters, the hyphen ("-"), or the underscore ("_").
They must have at least one character and are stripped of white-space and converted to lower case.
Metadata values are opaque text: Markdown statements (e.g., italics, entities, etc.) are copied as-is. The
values will have leading white-space stripped, i.e., space following the colon.
If multiple metadata keys resolve to the same name, the last invocation is retained. This check happens
after canonicalising the name by stripping spaces, converting to lower-case, and substituting unknown
characters.
Metadata values may be pasted into a document by referencing the [%key], such as using the above example,
again with the caveat that Markdown annotations (italics, etc.) are copied verbatim:
Stardate: 43917.4
It's currently stardate [%stardate].
Mathematics
Mathematics support is an extension of Markdown. The extension only describes how the math blocks begin
and end: the contained equations are usually in LaTeX and implemented in the front-end (e.g., HTML). There
are two types: inline and block. Both may occur anywhere in a text stream. Inline equations are rendered
as part of the text; block equations are rendered on their own.
This is an inline $f(x)$ function.
This is a block $$f(x)$$ function.
This is also an inline \\(f(x)\\) function.
This is also a block \\[f(x)\\] function.
Tables
Tables are a GFM (GitHub-flavoured Markdown) extension of the basic syntax. They consist of a table header
and body, and columns may be left, right, or centre justified.
| Officer | Rank |
| --------------: | -------------------- |
| Jean-Luc Picard | Captain |
| Worf | Lieutenant Commander |
| Data | Lieutenant Commander |
| William Riker | Commander |
The table header must be followed by a line of hyphens with at least three hyphen/colons per column.
Columns are separated by vertical bars. The colon indicates alignment: a colon at the beginning means left
justified; at the right for right justified, and both for centred.
The leading and trailing column separator is superfluous. Table data is not necessary, but the table
header is. The minimum table structure for the above is:
Officer | Rank
--:|---
Jean-Luc Picard | Captain
Table columns may contain arbitrary span elements.
Footnote Definition
Footnotes are a MMD (Multimarkdown) extension of the basic syntax. Footnote definitions may occur anywhere
in the text (except within blocks) and are “pointed to” by a Footnote Reference. They consist of the
footnote name (in square brackets, preceded by the caret), a colon, then everything remaining in the block
is the footnote content.
[^pt]:
Klingon insult, meaning something like "weirdo," deriving from
the verb "to be weird" (**taQ**), with and [sic] you (plural)
imperative prefix (**pe-**).
Footnote contents may be on the same line as the colon. The footnote name is rendered as a number. If a
footnote definition is not referred to, it is not printed.
HTML Blocks
Embedded HTML is discouraged, as it inhibits formatting into non-HTML output, but is still accepted.
Blocks of HTML must begin with a recognised HTML block-level element.
In the original Markdown, block-level elements were well-defined by HTML4. HTML5 elements are also
accepted, but as there is no concept of block-level in HTML5, these are non-canonical. Accepted elements
are <address>, <article>, <aside>, <blockquote>, <del>, <details>, <dialog>, <dd>, <div>, <dl>, <dt>,
<fieldset>, <figcaption>, <figure>, <footer>, <form>, <h1>, <h2>, <h3>, <h4>, <h5>, <h6>, <header>,
<hgroup>, <iframe>, <ins>, <li>, <main>, <math>, <nav>, <noscript>, <ol>, <p>, <pre>, <section>, <script>,
<style>, <table>, <ul>, and self-closing <hr />.
SPAN ELEMENTS
Span elements are inline elements (including normal text) within block elements, for example, a span of
emphasised text or a hyperlink. A span element cannot contain a block element, but can contain other span
elements.
Emphasis
There are two different styles of emphasis: strong, usually rendered as bold; and emphasis, usually
rendered as italics. This is confusing, so sometimes the former is referred to as a “double-emphasis”
while the latter is a “single-emphasis”.
Text surrounded by a single asterisk (“*”) or underscore (“_”), the single-emphasis variant, is
traditionally rendered with italics.
*Captain Picard*
_Captain Picard_
Text surrounded by a double asterisk (“**”) or underscore (“__”), the double-emphasis variant, is
traditionally rendered as bold.
**Jean-Luc Picard**
__Jean-Luc Picard__
Emphasis may occur within the middle of a word:
En*ter*prise
In order to produce a literal asterisk (“*”) or underscore (“_”) simply surround the character by white
space.
The ship * USS Enterprise * will not be emphasized
Two additional types of double-emphasis are the strike-through and highlight. These are produced by pairs
of tilde and equal characters, respectively:
~~Kirk~~Picard is the best ==captain==.
The highlight variant may be enabled in lowdown(1) with highlight parsing enabled. It's disabled by
default because if used at the beginning of a line it may be erroneously interpreted as a section.
Links
There are two types of links: inline and reference. In both cases, the linked text is denoted by square
brackets (“[]”). An inline link uses parentheses (“()”) containing the URL immediately following the
linked text in square brackets to invoke the link.
[text to link](https://bsd.lv)
Local references may be absolute or relative paths:
[Picard](/Picard)
A reference link, on the other hand, keeps the URL outside of the text — usually in the footnotes. Define
a reference link anywhere in a document by a title in square brackets (“[]”) followed a colon (“:”)
followed by the corresponding URL or path, then an optional title.
[link1]: https://www.bsd.lv/picard.jpg "Optional Title"
The title may be delimited with single quotes, double quotes, or parenthesis. It encompasses all text
until the last delimiter before the end of line, so it may contain delimiters. The title may be on its own
line.
Reference the link anywhere in your text using [text to the link] and the same [link title], both in square
brackets (“[]”) next to each other:
Text about [Captain Picard][link1].
References need not follow the definition: both may appear anywhere in relation to the other.
Reference and inline links may be followed by PHP Extra attributes.
Lowdown [homepage][home] or
[github](https://github.com/kristapsdz/lowdown){ .gh #link1 }.
[home]: https://kristaps.bsd.lv/lowdown { .home #link2 }
For inline links, the open brace must immediately follow the closing parenthesis. Attributes are separated
by spaces.
Values with a leading period (".class") are interpreted as HTML (CSS) classes, and values with a leading
pound symbol ("#id") are interpreted as HTML identifiers.
Automatic Links
Automatic links are links to URLs or emails addresses that do not require text to links; rather, the full
link or email address is inferred from the text. To invoke an automatic link, surround the link or email
address with angle brackets (“<>”), for example:
<https://bsd.lv/>
<kristaps@localhost>
Images
The image syntax resembles the links syntax. The key difference is that images require an exclamation mark
(“!”) before the text to link surrounded by square brackets (“[]”).
Just like with links, there are both inline and reference image links.
The inline style consists of an exclamation mark (“!”) followed by the alternate text (which may be empty)
surrounded by square brackets “([])” followed by the URL or the path in parentheses “(())”.
Unlike link text within square brackets, the alternate text is interpreted as-is. Thus, passing Markdown
or HTML entities will be passed directly to output (escaped according to output medium). Alternate text
may not begin with the caret (“^”) or percent (“%”), else they will be interpreted as footnote or metadata
references, respectively.
The parentheses may contain optional dimensions (widthx[height]) starting with an equal sign or a quoted
(single or double quotes) title in any order after the URL or path. These dimensions are pixel sizes.
The reference style definition consists of an image identifier surrounded by square brackets “([])”
followed by a colon “(:)” followed by an image URL or path to image and optional title attribute in double
quotation marks.
[image1]: https://bsd.lv/picard.jpg "Picture of Picard"
Invoking the image reference is as follows:
A picture of the captain: ![Captain Picard][image1]
As with regular reference links, the definition and references may occur anywhere in relation to each
other.
Images may also be followed by PHP Extra attributes for classes, identifiers, and width and height.
Implementation of these depends on the output medium.
{width=20% .class}
The open brace must immediately follow the closing parenthesis. Attributes are separated by spaces.
Value pairs "width=xx" and "height=xx" are interpreted as HTML (CSS) or LaTeX dimensions. These override
set pixel dimensions. Percentages are understood by both media; otherwise, dimension units are interpreted
according to the medium.
Values with a leading period (".class") are interpreted as HTML (CSS) classes, and values with a leading
pound symbol ("#id") are interpreted as HTML identifiers.
Code
In addition to code blocks, inline code spans may be specified within paragraphs or other block or span
elements. To invoke a span of code, surround the code using backtick quotes (“`”).
I need your IP address to scp you Picard pics.
Use the `ifconfig iwm0` command.
To include literal backticks (“`”) within a code of span, surround the code using multiple backticks
(“(``”).
``Here is a span of code with `backticks` inside it.``
If you have a literal backtick at the start or end of the span of code, leave a space between the literal
backtick and the delimiting backticks.
`` `So many backticks.` ``
Footnote Reference
Footnotes are a MMD (Multimarkdown) extension of the basic syntax. Footnote references point into a block-
level Footnote Definition. They consist of the footnote name in square brackets, preceded by the caret.
P'tahk[^pt], tell me who you are, or I will kill you right here!
The footnote name is rendered as a number. There may only be one footnote reference per definition. If a
footnote refers to an unknown definition, it is printed as-is.
Superscripts
Uses the caret (“^”) to start a superscript. The superscripted material continues to white-space or, if
starting with an open parenthesis, the close parenthesis.
Though a great book, Q^2 (Q^(squared)) isn't Star Trek canon.
HTML Content
While block-level HTML must begin with a recognised block-level HTML element, span-level HTML need only
begin and end with angle brackets, and not contain a hyperlink.
Thus, <p>, <Leonard Nimoy>, and <span class="foo"> are all accepted. Even malformed content, such as <span
class="foo> is accepted, so long as it begins and ends with angle brackets.
ESCAPES
Automatic Escapes
Output is automatically escaped depending upon the medium. For example, HTML output will properly escape
angle brackets “(<)” and ampersands “(&)” to produce conformant HTML. The same goes with man(7) output in
escaping leading periods and so forth.
Backslash Escapes
Backslash escapes render literal characters that would otherwise invoke a particular block or span element.
For example, surrounding a phrase with single asterisks renders it as an emphasis:
*Captain Picard*
However, if you want to invoke those italics as literal characters, escape those asterisks using
backslashes (“\”).
\*Captain Picard\*
The following characters may be escaped to produce literal text:
* asterisk
\ backslash
` backtick
{ curly brace
! exclamation mark
# hash mark
- minus sign
( parentheses
. period
+ plus sign
[ square bracket
_ underscore
TYPOGRAPHY
lowdown(1) renders certain character sequences for easier reading. This is called "smart formatting". The
following character sequences are converted to output-specific glyphs. The table shows whether the
sequences must be on word boundaries.
(c) copyright
(r) registered
(tm) trademark
(sm) service mark
... ellipsis
. . . ellipsis
--- em-dash
-- en-dash
1/4 one-quarter full word boundary
1/4th one-quarter full word boundary
3/4 three-quarters full word boundary
3/4th three-quarters full word boundary
3/4ths three-quarters full word boundary
1/2 one-half full word boundary
" left-double left word boundary
" right-double right word boundary
' left-single left word boundary
' right-single not left word boundary
Word boundaries are defined by white-space (including the end of blocks, such as paragraphs, or end of
file) or punctuation. Left word boundary refers to white-space or a left parenthesis or square bracket to
the left of the sequence. Right refers to white-space or punctuation to the right.
Smart quotes (single and double) are not context aware: using a left or right quote depends upon the
characters surrounding the quote, not whether a prior quote mark has already been used.
SEE ALSO
lowdown(1)
STANDARDS
The Markdown syntax accepted by lowdown(1) conforms to John Gruber's original Markdown implementation.
Extensions to the language are specifically noted. They include:
CommonMark: http://commonmark.org
GFM: https://github.github.com/gfm
Multimarkdown: http://fletcherpenney.net/multimarkdown
PHP Extra: https://michelf.ca/projects/php-markdown/extra
AUTHORS
The lowdown reference was originally written by Christina Sophonpanich and is maintained by Kristaps
Dzonsons <kristaps@bsd.lv>.