Practical International Data Management - Sorting code
A sorting code is related to postal codes in that it is used in addresses to allow sorting, for example to route mail to a certain postal centre or to distinguish streets with the same name in two different areas of the same settlement. It is not a postal code, and needs managing separately from postal codes for these important reasons:
An address may contain BOTH a postal code AND a sorting code. For example, in Belgian mailing addresses, a numeric sorting code after the place name may be used to indicate the post office containing the post office box, in an address block already containing a postal code. In France text such as CÉDEX is used as a sorting code in addition to postal codes.
Sorting codes do not cover the whole national territory. In Ireland, for example, sorting codes are used in Dublin but nowhere else.