function isHalfAlpha( alp){ // ******* ### isHelfAlpha *******

    var ref, i, r;
   
    r = true;
    ref = '._-01234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
   
    for( i = 0; i < alp.length; i ++){
   
        if( ref.indexOf( alp.charAt(i), 0) == -1){
    
            r = false;
            break;
    
        }
   
    }
  
    return r;
  
}  // ******* ### isHalfAlpha *******