The code assigned by Royal Mail to identify postal delivery areas across the United Kingdom.

POSTCODES may also be used to identify a GEOGRAPHIC AREA.

References:
The e-GIF version approved for use in NHS England is:
Government Data Standards Catalogue: (GDSC), Version 2.1, Agreed 1 September 2002.
Further information can be found on the Cabinet Office website

This attribute is also known by these names:
ContextAlias
pluralPOSTCODES