+
+## Implementations
+
+There are several implementations of markdown support that can be used by
+this plugin. In order of preference:
+
+* [Discount](http://www.pell.portland.or.us/~orc/Code/discount/),
+ via the [[!cpan Text::Markdown::Discount]] perl module.
+ This implementation is considered to be the default and is strongly
+ recommended, but it is not mandatory because it requires an external
+ C library.
+* The [[!cpan Text::Markdown]] perl module.
+* The [original version of markdown](http://daringfireball.net/projects/markdown/).
+
+[[!cpan Text::MultiMarkdown]] can be used in order to use tables, footnotes,
+and other new features from the markdown variant called
+[multimarkdown](http://fletcherpenney.net/MultiMarkdown/) (some of which
+are also available in the recommended implementation, Discount). Multimarkdown is
+not enabled by default, but can be turned on via the `multimarkdown` option
+in the setup file. Note that multimarkdown's metadata and wikilinks
+features are disabled when it's used with ikiwiki. Also note that if the
+`multimarkdown` option is enabled, it takes priority over Discount, which
+might cause formatting that is understood by Discount to be ignored.
+
+
+## Advanced options
+
+* `nodiscount`: If set to 1, Text::Markdown::Discount will not be used
+ even if it is available. The default is to use Discount if available,
+ and this is recommended.
+* `multimarkdown`: If set to 1, Text::MultiMarkdown will be used in
+ preference to Text::Markdown::Discount. The default is to not use
+ MultiMarkdown, and this is recommended.
+* `mdwn_footnotes`: If set to 1, implementations that support it will
+ recognise the footnote syntax originating in PHP Markdown Extra, with
+ `Footnote reference[^1]` and `[^1]: Footnote definition`. The default
+ is 1.
+* `mdwn_alpha_lists`: If set to 1, Text::Markdown::Discount will
+ accept letters as well as numbers in ordered list markers. The
+ default is 0, to avoid unintended parsing of lines that happen
+ to begin with a letter and a dot, such as "C. S. Lewis was an
+ author" or "M. Descartes was a philosopher".