Server Side Suitescript Questions dealing with update Item Records

Hello all,

I am writing a script that will update all the item records on a PO after submission.  What I want to do is save the PO# on the item record so that I know what the last PO the item was on.

Here is the code snippets so far:

   // After Purchase Order is created, update the item records that are on the PO, so that it makes note of the last PO is was on  function afterSavePurchaseOrder(type) {   var poRecord = nlapiGetNewRecord();   var poID = poRecord.getId();   var itemid = 0;   if (type = 'Create') {    for (var i = 1; i <= poRecord.getLineItemCount('item'); i++) {     itemid = poRecord.getLineItemValue('item', ????, i) //should get the internal id of the item     updateItemPOField(itemid, poID);    }   }  }    // Update Most Recent PO field for Item, find by internal id  function updateItemPOField(item_id, PO_id){   var itemRecord = nlapiLoadRecord('item', item_id);   itemRecord.nlapiSetFieldValue('custitem_last_po', PO_id); //can I