function validLetterNumber(direc) {  
	validChars = "-_abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; 
	spaces=0;
	dots=0;
	letters=0;
	for (z=0; z<direc.length; z++) { 
		charOK=false;
		for (i=0; i<validChars.length; i++) {
				if (direc.charAt(z)== validChars.charAt(i) ) { 
					charOK=true;
					break;
				}  
		}
		if (!charOK)  return false;  
		letters++  
	} 
	if (letters==0) {
		return false;
	}
	return true;
}
