I found this info on CIC website:
In either case, you will have to show the officer:
- your passport, travel or identity document (including your visa sticker, if you have one), and
- your Confirmation of Permanent Residence, permanent resident visa, Certificat de sélection du Québec (CSQ), letter of introduction or any instructions from the Canadian visa office, and
- your proof of legal status in Canada, such as a valid work permit, study permit, temporary resident permit, or visitor document, or any immigration document you have (whether valid or not), or
- proof of implied status (if you applied to extend your stay before it ended). Proof of this status may include:
- payment receipt,
- copy of your application to extend your stay,
- printout of online application, or
- proof of mailing.
Note: You must leave Canada, enter another country and re-enter Canada to become a permanent resident at an international airport or Canadian land border.
*I also saw that someone said we need to present a proof of address in Canada. Also POF but i think it does not apply to CEC category.