I have received RPRF on September 26th saying that my application is eligible in the Class for which it was submitted. Yeeee

However, a week before that, Sept 19th, CPC has sent me another email in which they are asking additional documents for my partner;
T4: A copy of the Canadian Revenue Agency T4 form for 2013
Notice of Assessment: A copy of the Canadian Revenue Agency Notice of tax Assessment for 2013
Employment Letter: An official document printed on company letterhead stating that you, in whose name the letter is printed, will be employed in Canada for a specified period of time by that company. It must list your name, the details of your employment in Canada.
Please provide information on your employment history .
We got all documents from Revenue Canada Agency but does anyone has any idea what is Employment History and Employment Letter?
My boyfriend was obligated to work for his boss because she did LMO. Finally in April this year, after two and half years working at that place, he decided to quit. He couldn't work at that place any more because she was taking the advantage of his situation. At this moment he is unemployed, because he's not allowed to work for anyone else, but he does have a job offer from another company.
My question is, since he can't get Employment Letter from his previous boss, would it be ok to present just T4, Notice of Assessment and Job Offer Letter?