BS7666 is a British Standard that sets out the guidelines upon which are built the Local Land and Property Gazetteers (LLPGs) and Local Street Gazetteers (LSGs). It set out standards by which to record Basic Land and Property Units (BLPUs), which include within them a Unique Property Reference Number (UPRN), grid co-ordinates and one or more Land Property Identifiers (LPIs).
Because of the standardised way that BS7666 enforces the recording of street and land & property information, each LLPG or LSG are able to be amalgamated into their corresponding national datasets i.e. the National Land and Property Gazetteer (NLPG) and the National Street Gazetteer (NSG).
BS7666 does not distinguish between residential properties that are vacant or occupied, if a plot of land is developed or vacant, whether the area is urban or rural, and addressable properties and non-addressable entities such as communications masts.