6.3.11.1
The RPC indicates the confidence level of the coordinates as described below:
1
Visual centre – see Section 6.3.11.2
2
General internal point – see Section 6.3.11.3
3
SW corner of referenced 100m grid square
4
Start of referenced Street
5
General point based on postcode unit
9
Centre of SNN Authority area
6.3.11.2
RPC = 1 indicates that the Authority Address Custodian is confident of the location of the coordinates as the visual centre of the primary building or structure or area (land) of the BLPU.
6.3.11.3
The Authority Address Custodian must decide if a primary building or structure exists within the BLPU.
6.3.11.4
If more than one building or structure exists within the BLPU, the Authority Address Custodian must decide which is the primary one. This building or structure may happen to be near the delivery point for mail but is not so in all cases.
6.3.11.5
If a BLPU has a primary building or structure and that primary building or structure is visible on the base mapping, then the following rules apply:
- The BLPU coordinate must be placed in the visual centre of the primary building or structure.
- An RPC = 1 – visual centre must be allocated.
6.3.11.6
If a BLPU does not have a primary building or structure then the following rule applies:
- The coordinate must be placed within the centre of the extent which is represented by the BLPU and an RPC = 1 – visual centre must be allocated.
6.3.11.7
If a BLPU is created for a site, which is in addition to an address parent BLPU for the site, for example a hospital, then the following rules apply:
- The BLPU coordinate must be placed in the visual centre of the polygon extent which represents the site.
- An RPC = 1 – visual centre must be allocated.
- Creation of this BLPU is not mandatory and depends on the SNN Authority’s use of BLPU polygon extents.
- The description of this BLPU must be clearly differentiated from the description of the address parent BLPU to avoid confusion for the user. For, example the description should be described as ‘The John Radcliffe Hospital site’.
- This BLPU must be classified as PP (property shell).
6.3.11.8
RPC = 2 indicates one of the following:
- The coordinates are located in the general internal extent of the primary building or structure or area (land) of the BLPU.
- The coordinates represent the most spatially accurate position pending base mapping updates.
6.3.11.9
If a BLPU is created for a building or structure and the Authority Address Custodian is unable to establish where the visual centre of the building is, for example if the Authority Address Custodian needs to see the building on the base mapping, then the following rules apply:
- The BLPU coordinate must be placed in the position to the best of the Authority Address Custodian’s knowledge.
- An RPC = 2 – general internal point must be allocated.
6.3.11.10
These records must be corrected over time as the base mapping is updated or further intelligence is received.
6.3.11.11
RPC = 4 must only be assigned to new BLPUs created which represent a Street BLPU Record with Classification BLPU_CLASS = PS. The exception to this is that RPC = 4 may also be used as a temporary code if the Authority Address Custodian is unable to enter a Record to establish accurate enough coordinates to use RPC = 1 or 2 for an Object with a Classification of other than BLPU_CLASS = PS.
6.3.11.12
RPC = 3, 5 or 9 must not be assigned when new BLPUs are created. The RPC assigned to all BLPUs must have a minimum RPC = 1 or 2, or 4 for a Street BLPU. For guidance on improving RPCs, see Appendix G.