I have the same question:
I have reference letter from my previous company. It states my last designation in the company, my hire and resignation date, last withdrawn salary. But it does not mention the word "full-time" or hours worked. Also it does not mention job description or job duties, just my title as "software developer" or "web developer" with list of technologies I worked with.
My work experiences in different companies related to for NOC 2171, 2173, 2174. Please let me know how can I proof my job duties.