function checkform(){
	var arrnames = new Array(10);
	var arrerrores = new Array(10);
	
	arrnames[0] = "nombre"
	arrnames[1] = "apellidos"
	arrnames[2] = "direccion"
	arrnames[3] = "ciudad"
	arrnames[4] = "pais"
	arrnames[5] = "cursoelegido"
	arrnames[6] = "cursosdesde"
	arrnames[7] = "cursoshasta"
	arrnames[8] = "tipoalojamiento"
	arrnames[9] = "conocimientosespanol"
	arrnames[10] = "securityCode"
	
	arrerrores[0] = "You must enter Name"; 
	arrerrores[1] = "You must enter Last name"; 
	arrerrores[2] = "Write your address, please"; 
	arrerrores[3] = "City has to be especified"; 
	arrerrores[4] = "You must write your Country"; 
	arrerrores[5] = "You must select at least one course from the list"; 
	arrerrores[6] = "You must write date of course"; 
	arrerrores[7] = "You must write date of course"; 
	arrerrores[8] = "Especify Accommodation, please";
	arrerrores[10] = "You must enter the security code"

// cas5 -> el select multiple
	for(a=0;a<10;a++)
	{
		if(a==5)		
		{
			if(document.getElementById(arrnames[a]).selectedIndex == -1)
			{
				alert(arrerrores[a]);
				document.getElementById(arrnames[a]).focus();
				return false;	
			}
		}
		else
		{
			if(document.getElementById(arrnames[a]).value == "")
			{
				alert(arrerrores[a]);
				document.getElementById(arrnames[a]).focus();
				return false;			
			}
		}
	}
}