At each Census, Collection Districts may be redesigned to accommodate growth in population or to conform to other administrative data. To assist users to compare data for Collection Districts which changed between the 1996 to 2006 Censuses, a comparability code has been allocated to pairs of Collection Districts. The resultant listing, which includes all Collection Districts for both 1996 and 2006, indicates if the CDs between the 1996 and 2006 Censuses are comparable or not comparable. The data is supplied as a comma delimited text file with an accompanying explanation of the meaning of the codes.