Adjacency Table

Non-Geographic postcodes

As the data is sourced from actual boundaries, it means the adjacency table will not include non-geographic Postcode Sectors.

Recognition of Inland Water

Inland water bodies are not included as 'holes' in Geoplan boundaries, although there are four exceptions - Loch of Strom on Shetland, Loch Lomond in Scotland, Lough Neagh in Northern Ireland and Strangford Sea Loch, also in Northern Ireland, which has been made into a closed Loch.

Where Postcode sectors occur close to inland waters the sector boundary runs along the centre of the water body. Alternatively, if settlements alongside the lake/loch have different postal sectors because of their accessibility/relative distances to postal delivery offices the sector may cut across the water body to accommodate this. Postcode Boundaries often follow man-made and natural features, but are not intended to represent them.

Coastline Source

Larger estuaries such as the Firth of Tay and Forth, Tyne, Thames and Exe are included in Geoplan boundaries, although not necessarily up to their tidal limit. Geoplan often cuts across smaller estuaries, although on some a small inlet may be shown to gain a general outline of the coast.

Isle of Man

The Geoplan product also contains the Isle of Man Sectors IM1 0, IM2 0, IM3 0 and IM8 0, but do not actually exist as real codes. This is because, although the extents of the Districts IM1, IM2, IM3 and IM8 are known, the boundaries of the Sectors within them cannot be determined. No maps exist at the Isle of Man Post Office which show these Sectors, so the non-existent Sectors listed above were created by Geoplan to take their place