if (type=='item'){
var subRecord = nlapiViewLineItemSubrecord('item', 'inventorydetail',1); //view inventory details
var lotnumber = subRecord.nlapiGetCurrentLineItemValue('inventoryassignment','issueinventorynumber'); //get lot number
var expdate = subRecord.nlapiGetCurrentLineItemValue('inventoryassignment','expirationdate'); //get expiration date