It is the note that showing which part of your application has been done and which one is not . You can find information in following thread
https://www.canadavisa.com/canada-immigration-discussion-board/threads/how-to-order-gcms-notes-step-by-step-process.513893/
Thanks and good luck with yours. I know if I send one it will get stuck there just like my application because they are so busy with taking vacation and sleeping on the job all the time that they don't have time to do their job. After the new government changed the rule to 3/5, they also recruited enough resources, so being busy is not a valid excuse especially when many cases are going over the 12 months period. It is unacceptable to see so many cases are waiting for a test invite or oath for 14, 16, or 19 months. They do not even care enough to expedite when people call them and ask them to at least explain the reason for the major delay. Their solution is easy, they just say the same BS like your case is an unusual case or it’s a case by case scenario. They assume applicants don’t know better and have not worked in government or other organizations to know that such BS simply means someone is not doing their job, and wasting taxpayers’ money.