function checkFields() {
missinginfo = "";
if(document.form.curs.value == "" || 
document.form.curs.value == "") {
missinginfo += "\n     -  Curs";
}
if (document.form.dni.value == "") {
missinginfo += "\n     -  DNI-NIE";
}
if(document.form.nom.value == "") {
missinginfo += "\n     -  Nom";
}
if (document.form.cognom1.value == "") {
missinginfo += "\n     -  1r cognom";
}
if (document.form.carrer.value == "") {
missinginfo += "\n     -  Adreça";
}
if(document.form.poblacio.value == "") {
missinginfo += "\n     -  Població";
}
if(document.form.comarca.value == "") {
missinginfo += "\n     -  Comarca";
}
if (document.form.cp.value == "") {
missinginfo += "\n     -  C.P.";
}
if (document.form.email.value == "") {
missinginfo += "\n     -  E-mail";
}
if(document.form.telefon.value == "") {
missinginfo += "\n     -  Telèfon";
}
if(document.form.lloctreball.value == "") {
missinginfo += "\n     -  Lloc de treball";
}
if(document.form.adrecatreball.value == "") {
missinginfo += "\n     -  Adreça de treball";
}
if(document.form.telefontreball.value == "") {
missinginfo += "\n     -  Telèfon de treball";
}

if (missinginfo != "") {
missinginfo ="_____________________________\n" +
"Aquests camps són obligatoris\n" +
missinginfo + "\n_____________________________" +
"\nSi us plau, torna a escriure!";
alert(missinginfo);
return false;
}
else return true;
}