The statistics made available from the 1991 Census were more extensive than those produced for any previous population Census in Great Britain. The 1991 definitions and explanatory notes from the Office of Population Census and Surveys (now called Office for National Statistics (ONS)) and General Register Office for Scotland (GRO(S)) are available for viewing and printing via the Question Bank [Note: These links open in a new window]
A similar document was produced to accompany the 1981 Census allowing comparisons to be made in definitions and terms between the two censuses:1981 Census, Definitions, Great Britain, HMSO 1981.