Xrm.Mobile.offline.updateRecord lookup field

Hi,

What is the proper value of the lookup field to be set for Xrm.Mobile.offline.updateRecord call?

Documentation says nothing and I'm struggling to update an entity.

Tried:

var data  = {lookupFiled: "ID of entity"}

var data  = {lookupFiled: "@odata.bind/EntityName(ID of entity)"}

var data  = {lookupFiled: "EntityName(ID of entity)"}