The documentation would start with a letter from your company proving (in detail, where necessary) that you meet these criteria:
- Establish objectives for the company and formulate or approve policies and programs
- Authorize and organize the establishment of major departments and associated senior staff positions
- Allocate material, human and financial resources to implement organizational policies and programs; establish financial and administrative controls; formulate and approve promotional campaigns; and approve overall personnel planning
- Select middle managers, directors or other executive staff
- Co-ordinate the work of regions, divisions or departments
- Represent the company, or delegate representatives to act on behalf of the company, in negotiations or other official functions.
If you own a P/L or a LoB, add that to the letter. Or perhaps you control a million $+ budget.. basically all the things that will prove you are not just a middle manager but are much more senior.
Additional supporting documentation might be things like a copy of your Org. chart showing your direct/indirect reports, your pay statements for the past three months, potentially a letter from the CEO of your Canadian division stating that you are in fact a Senior Exec. in the Canadian org. All of this can be attached to one document.
I'd recommend you get some professional help as well. Even if your company lawyers aren't helping, you can go to your own immigration lawyer/consultant. They can help you craft a really strong application, and give you examples of successful applications they may have filed in the past.
It's nothing that onerous, but since you get 200 points for this, IRCC is wont to examine a NOC 00 application somewhat carefully to make sure you actually do qualify.
I'm assuming you are in no rush - take your time to put this together, or get some good professional help.