Horizontal ruler:\\
{{{----}}}
gives you:
----


Paragraphs are delimitted by a blank line.
{{{This is Paragraph 1

This is Paragraph 2
}}}
gives you:

This is Paragraph 1

This is Paragraph 2

----

Forced Line Break: 
{{{This is first line,\\this is second line!}}}

gives you:

This is first line,\\this is second line!

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Hyperlinks
{{{[~WikiPage] , [http://external.url], [~WikiPage#~SomeChapter]}}}
gives you:

[~WikiPage] , [http://external.url], [~WikiPage#~SomeChapter]

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Text with a hyperlink
{{{[some-text|link]}}}
gives you:

[Visit Yahoo|http://yahoo.com]