function ShowReg(idObj,idxObj) { 
//drop down list
var Obj1=document.getElementById(idObj);
    for (i=0;i<Obj1.length;i++)
    {
        if (i==idxObj){
            document.getElementById("Period " + i).style.display="block";
        }else{
            document.getElementById("Period " + i).style.display="none";
        }        
    }   
   
}