Importing events for tracker based program with registration.

Hi Devs,
I am importing events for tracker based programs using the dhis2 csv import. I am getting an error that trackedentityinstance id not provided. While I can get the trackedentityinstanceid, I am not sure in which column I should place it in. I have checked the web api csv import format in the docs and it does not specify thus either. I am using v2.28. Please help