offline data that's not necessarily linked to facebook but linked to some device they went to facebook on, is that right? >> i want to make sure we get this right. i want to have my team follow up with you on that afterwards. >> that doesn't seem that complicated to me. you understand this better than i do, but maybe explain to me why that's complicated. do you track devices that an individual who uses facebook has that is connected to the device that they use for their facebook connection but not necessarily connected to facebook. >> i'm not sure of the answer to that question. >> really? >> yes. there may be some data that is necessary to provide the service that we do, but i don't have that sitting here today. so that's something that i would want to follow up. >> the ftc last year flagged cross device tracking as one of their concerns, generally that