It is important to understand that Nigeria's postcode system is grouped into 3 categories;

• Urban Postcodes
• Rural Postcodes
• Facility Postcodes

The category names are pretty much self explanotary in that 'Urban Postcodes' represents postcodes allocated to the urban areas, 'Rural Postcodes' represents those postcodes allocated to the rural areas, whilst 'Facility Postcodes' represents postcodes assigned to a NiPost Office Facility.