Local Land and Property Gazetteer - Iahub.net

5. Hierarchical Relationships5.1 Introduction5.1.1 This section seeks to clarify Best Practice when dealing with hierarchicalrelationships between land and properties. The advice in this sectionrelates to the textual attributes contained within LPIs, and not the BLPUextents held within GIS. The following terms are used: -• Parent BLPU: This is a BLPU/LPI pair where the LPI contains an entryin the PAON but no entry in the SAON fields.• Child BLPU: This is a BLPU/LPI pair where the LPI contains an entry inboth the PAON and the SAON fields5.1.2 The following relationship should be enforced between the parent andchild BLPU“A child BLPU can only be created where a parent BLPU already existswith the same PAON and USRN.”5.1.3 The child BLPU should therefore inherit the PAON and USRN (not thePost Code) from the parent to avoid inconsistency. This is reflected inpara 7.3.3 of BS7666 part 2. The following diagram illustrates therelationship.SingleParent BLPUManyChild BLPUsBLPU UPRN BLPU UPRN *Is different to parentLPI UPRN LPI UPRNLPI SAON *blank LPI SAON *requiredLPI PAON LPI PAON *same as Parent BLPULPI USRN LPI USRN *same as Parent BLPULPI Post Code LPI Post Code *can be different to parentLPI Etc LPI Etc5.1.4 A child BLPU cannot exist without there being a parent BLPU. Where aproperty is subdivided into two flats a third entry for the building shellmust be created first. Such “building shell” records can be flagged asnon-addressable to prevent post being sent to it where the LLPG isused for generating mailing addresses.Version : 4Date: 18/02/05 Page 24