For CANSIM Table 051-0001 <http://www5.statcan.gc.ca/cansim/a26?lang=eng&retrLang=eng&id=0510001&paSer=&pattern=&stByVal=1&p1=1&p2=-1&tabMode=dataTable&csid=> Footnote 1 references Postcensal estimates are based on the 2006 Census counts, etc. I am assuming for earlier years it is for the closest preceding Census? I think I understand why only 2006 is referenced as the default display only displays years post 2006. Am I correct in interpreting that 1999--by way of example- would be rebased based on the 1996 Census?
Intercensal estimates are estimates of population for reference dates between two censuses. For 1999, it would be between 1996 and 2001. They are produced following each census in order to reconcile previous postcensal estimates with the new census counts adjusted for CNU, thus assuring the internal consistency of the estimation system.
Please refer to section 1.2.1 for more detail <http://www.statcan.gc.ca/pub/91-528-x/2011001/ch/ch1-eng.htm>.