11.9.1.1
The advice in this section relates to the textual attributes contained within Addressable Objects which create hierarchical relationships between addresses.
11.9.1.2
A Parent Child relationship exists if one BLPU is identified by reference to another BLPU. The LPI of the Parent record shall contain a PAO only and the LPI of the Child record shall contain both a SAO and a PAO. In most cases the Child inherits the PAO from its Parent.
11.9.1.3
If the hierarchy extends to a third or fourth level, then the entry in the PAO does not have to be identical for all records within the structure.
11.9.1.4
A Parent Record must be created first, and the relationship is established when a Child Record is created and an existing UPRN is recorded in the Parent UPRN field.
11.9.1.5
A historical child BLPU may be linked to a Parent Approved BLPU. However, a Parent Historical BLPU shall not be referenced by a Child Approved BLPU.
11.9.1.6
If an LPI with an entry in the SAO is made historical, and the BLPU remains live, then the relationship with the existing Parent must be broken.
11.9.1.7
In a Parent / Child relationship a Parent BLPU is represented by an LPI that contains an entry in the PAO but no entry in the SAO.
11.9.1.8
A Child BLPU is represented by an LPI that contains an entry in both the SAO and PAO. This LPI must have a LOGICAL_STATUS = 1, 3 or 6 - Approved Preferred, Alternative or Provisional.
11.9.1.9
If a Parent BLPU is created for an Object solely to provide a holding Record for a group of properties, the BLPU Classification BLPU_CLASS = “PP” must be used for the Parent Property Shell.
11.9.1.10
If a Parent BLPU is created for an Object which does exist in the real world the appropriate Classification codes must be used regardless of the Object’s status as a Parent BLPU, for example; an airport referenced by several Child BLPUs is classified as BLPU_CLASS = “CT01”.
11.9.1.11
This is a conditional requirement. Any BLPU that is referenced using a SAO in its associated LPI Record must contain the UPRN of its Parent BLPU in the PARENT_UPRN Field. There is no requirement for the Child BLPU to share or inherit an identical PAO or USRN from the Parent BLPU. This methodology provides a framework to extend the hierarchical relationship to grandchild and great grandchild Records for buildings in multiple occupation, for example airport complexes or university campus sites.
11.9.1.12
A maximum of four levels can exist in the hierarchy:
- PARENT – The top level of a BLPU hierarchy.
- CHILD – The second level of a BLPU hierarchy.
- GRANDCHILD – The third level of a BLPU hierarchy.
- GREAT GRANDCHILD – The fourth level of a BLPU hierarchy.
11.9.1.13
The PAO does not need to be identical for each level of the BLPU hierarchy. This means that multiple levels can be combined into the PAO and allows for truncated versions of an address element to be displayed, thereby ensuring that a meaningful address can be viewed by a user, regardless of the hierarchy behind the BLPU. For example, Terminal 1 Heathrow Airport may be shortened in the LPI relating to the BLPU in the next level down in the hierarchy to Terminal 1 Heathrow.
11.9.1.14
If there are 3 or 4 levels in a BLPU hierarchy where grandchild and great grandchild Records exist, the following rules must be applied:
- If 3 levels are required the PAO for the grandchild Record should be inherited from the Parent Record. The SAO should include reference to the bottom two levels of the hierarchy that is both the Child Record and itself, for example:
PARENT
UPRN 1
“University of Nottingham”
CHILD
UPRN 2
“Lenton Hall”
GRANDCHILD
UPRN 3
“Flat 1”
PAO
“University of Nottingham”
SAO
PAO
“University of Nottingham”
SAO
“Lenton Hall”
PAO
“University of Nottingham”
SAO
“Flat 1 Lenton Hall”
11.9.1.15
If 4 levels are required the PAO for the great grandchild Record should be inherited from the top two levels of the hierarchy. The SAO should include reference to the bottom two levels of the hierarchy that is both the grandchild Record and itself, for example:
PARENT
UPRN 1
“Gatwick Airport”
CHILD
UPRN 2
“North Terminal”
GRANDCHILD
UPRN 3
“Departure Building”
GREAT GRANDCHILD
UPRN 4
“Kiosk 1”
PAO
“Gatwick Airport”
SAO
PAO
“Gatwick Airport”
SAO
“North Terminal”
PAO
“Gatwick Airport”
SAO
“Departure Building North Terminal”
PAO
“North Terminal Gatwick Airport”
SAO
“Kiosk 1 Departure Building”
11.9.1.16
In the case of sites which contain Street Names, it can be appropriate to enter the site as a town or locality to allow for sensible addresses to be constructed where many levels of hierarchy exist.