Please read the FAQ hereI have question. In current website there is one requirement,
9. Police certificate(s) (as required)
You are required to provide a police certificate for each country, other than Canada, where you were present for a total of 183 days or more during the four (4) years immediately before the date of your application.
Is this will be change to 3 years or still will be 4 years?
http://www.canadavisa.com/canada-immigration-discussion-board/threads/changes-on-oct-11-2017-executive-summary-faq.520982/