Before revision: Here is an example of an IFR clearance for a Cessna aircraft traveling from Palo Alto airport (KPAO) to Stockton airport (KSCK) , in the United States.The precise format used in issuing IFR clearances over the radio varies greatly between jurisdictions, however, all of them contain a clearance limit, here, Stockton airport, beyond which the aircraft may not proceed without further clearance.
After revision: Here is an example of an IFR clearance for a Cessna aircraft traveling from Palo Alto airport (KPAO) to Stockton airport (KSCK)