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This is a critical concept. The node property will always be the same for any given node. The element property will be somewhat dynamic, usually a regular expression will parse and 'capture' it. The most comment element example would be an interface; gig0/0 versus gig0/1. The stateful property is necessary because the same element may have different events; consider an interface down event versus an OSPF event on the same element (gig0/0).
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