This is an exact-fit lookup file between Output Areas as at December 2011 and Output Areas as at December 2021 and Local Authority Districts as at December 2022 in England and Wales. This product has been provided with a 'change indicator' field, that define the lookup between 2011 and 2021 OA. This field indicates which output areas / super output areas have changed between 2011 and 2021. There are four designated categories to describe the changes, and these are as follows:U - No Change from 2011 to 2021. This means that direct comparisons can be made between these 2011 and 2021 OA. S - Split. This means that the 2011 OA has been split into two or more 2021 OA. There will be one record for each of the 2021 OA that the 2011 OA has been split into. This means direct comparisons can be made between estimates for the single 2011 OA and the estimates from the aggregated 2021 OA.M - Merged. 2011 OA have been merged with another one or more 2011 OA to form a single 2021 OA. This means direct comparisons can be made between the aggregated 2011 OAs’ estimates and the single 2021 OA’s estimates.X - The relationship between 2011 and 2021 OA is irregular and fragmented. This has occurred where 2011 OA have been redesigned because of local authority district boundary changes, or to improve their social homogeneity. These can’t be easily mapped to equivalent 2021 OA like the regular splits (S) and merges (M), and therefore like for like comparisons of estimates for 2011 OA and 2021 OA are not possible.  Field Names – OA11CD, CHNGIND, OA21CD, LAD22CD, LAD22NM, LAD22NMW Field Types – Text, Text, Text, Text, Text, TextField Lengths – 9, 1, 9, 9, 35, 24