移民加拿大:工作证明信必须是original 吗?

Appendix A Checklist: 一开始说: send photocopies document except the police certificate, which must be originals. 但在第七项work experience 又说:Original and up-to-date letters of reference from your past and current employers.
有点犯糊塗>

请教有经验的大侠: 到底复印件行吗? 谢谢!