A function is a task, duty or responsibility of a position. An essential function is a task, duty or responsibility of a position that is so necessary to the position that the purpose of the position cannot be accomplished if it is removed.
Candidates being considered for a classified position must be provided with a description of the essential functions of the position.
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A marginal task, duty or responsibility of a position is one that can be reassigned to another position without compromising the purpose of the position.