function checkSearch(theForm){
	var chiave_reg_exp = /([a-zA-Z0-9])/;

	if ((theForm.chiave.value==0) && (theForm.chiave.value.length<=0)) {
		return false
	}
		
	if ((theForm.chiave.value.length > 0) && (!chiave_reg_exp.test(theForm.chiave.value))){
		return false
	}

}