Usually preformatted is used by programmers to show and discuss sourcecode. The example below shows how non technical users might use this element for 

!Guitar Chords

see [http://commons.wikimedia.org/wiki/Category:Chords_in_guitar]
{{{
Guitar Chord C:

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||-0-|---|---|
||---|-0-|---|
||---|---|-0-|
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}}}