In jQuery Validation plugin dependency-expression callback function syntax

Hi all.
Here [url]http://docs.jquery.com/Plugins/Validation[/url] method required( dependency-expression ) Returns: Boolean
Makes the element required, depending on the result of the given expression.

is described,but the link is dead and shows error :
Database error
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A database query syntax error has occurred. This may indicate a bug in the software. The last attempted database query was:
(SQL query hidden)

Which is correct syntax of dependency-expression callback function ?

Actually I want using jQuery Validation plugin verify is name of entered dictionary name is unique in database…I think dependency-expression callback function is suitable for it…

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