I believe 0601 responsibilities are those that would require someone to be at a very high post in a company,like COOs, CFOs, etc. If you have already left the company, you can talk with the HR what kind of responsibilities will they write in your experience letter. Alternatively, you can make a draft of responsibilities that you believe you actually handle and that matches with one of the job codes. Then you can send this draft to your HR asking if they will write these in experience letter.