Mark property soon. Stolen property that is unmarked can be easily fenced. Computers that are untagged are easy to fence. Airlines can use tagged baggage. Insurance companies use tagged keyfobs and marked keyrings for promotional incentives and promotional gifts.
Careful travellers mark all their property before flying from home.
Door entry smartcards can also be tagged. Smartcards can be specially printed with magnetic strips. Smartcards access is controlled but still safe if a person loses the Smartcard. Travelling Salesmen use tagged property. Fences dont buy marked or tagged stolen goods.