The dormant flag is one of the things that allow the agents to look at additional SIR records, and if it hasn't been used in a long time, it's one of the extra factors they look at when they're agreeing to reactivate a SIN. If there's something that doesn't fall right, if you have an individual who, for example, doesn't correspond with the documents or any of the facts of the situation when they're coming in, then you'll refer it to our national identity centre for investigation.
On April 1st, 2014. See this statement in context.