This is the regulation of Immigration and Refugee protection :
While your application for the Phd program meets one of the requirements of the Ministerial Instructions now in effect, to be eligible for processing, your work experience must still meet the minimal requirements as defined in subsection 75(2) of the Immigration and Refugee Protection Regulations that states that a foreign national is a skilled worker if:
a) within the ten years preceding the date of their application for a permanent resident visa, they, have at least one year of continuous full-time (37.5 hours/week) employment experience as described in subsection 80(7), or the equivalent in continuous part-time employment in one or more occupations, other than a restricted occupation, that are listed in Skill Type 0 Management Occupations or Skill Levels A or B of the National Occupational Classification matrix;
b) during that period of employment they performed the actions described in the lead statement for the occupation as set out in the occupational descriptions of the National Occupational Classification; and
c) during that period of employment they performed a substantial number of the main duties of the occupation as set out in the occupational descriptions of the National Occupational Classification, including all of the essential duties.
If you still have any confusion, plz ask since I have really bad experience regarding this work experience issue when I applied first time and was rejected for proper documents. As a whole, you have to have at least one year work experience, doesn't matter part time or full time but it has to be continuous and have to a have at least a total of 1950hrs work experience. But thankfully, I heard many of ours application were accepted just with the TA and RA experience. You have to make sure your letter contains all your job responsibilities, salary amount, working hours very specifically.
Thanks