decis decemb applic articl regul eec administr commiss european commun social secur migrant worker regard articl council regul eec june applic social secur scheme emploi person emploi person member famili move commun made respons deal administr question question interpret aris regul eec subsequ regul purpos aggreg articl regul eec list convers rule adher period insur complet legisl member state express unit legisl member state clear system equival unit provid articl regul eec institut carri convers account data transmit data convers base decid period insur basi convers provid articl regul eec commun institut member state legisl period complet mean convers carri singl oper cover period period commun aggreg year period commun year year basi decis publish offici journal european commun applic dai month public chairman administr commiss manassi oj oj