Yes, Vitrium does track analytics data when a user accesses a document in offline mode. Vitrium will track all the usual analytics - pages visited, time spent on each page, read-through-rate, etc. - and then process it the next time that user comes back online and opens the same document in the same browser. This condition needs to be met for that analytics data to reach Vitrium’s servers. Once it does, the data enters the queue and may take some time to process but it will eventually show up in the detailed analytics reports.