Tracking lesson completion into the LMS

Hi community!

I am working on a course with a number of differnt lessons within.

I wanted to pass the lesson completion into the LMS, but currently only passes the course or "action_ID" which is the same across all lessons.

Learning you can add custom parameters at the end of the launch link query string - and any additional paramaters will be passed back. 

Does anyone have an en example of a custom parameter that would pass the "lessons"? Each has a unique identifier, I just want to collect the variable across each lesson to also be passed into the LMS.

Any help would be great! Thanks,