Scan is one of six standard Action Bar actions available on all Federation and Dominion starships.

The ship taking the action places a Scan Token next its base. 

While the token is present, any ship attacked by the ship with the token rolls one less defense die.  Unlike other Action tokens the token does not need to be spent to gain this benefit, although other Upgrades may require the Scan Token to be spent for other benefits.

Any unspent Scan Tokens are removed during the End Phase.