A unique reference number given to a passport book issued by Security Printing and Systems (SPSL) or the United Kingdom Passport Agency.

The digit allows identification of the place of issue.

References:
The e-GIF version approved for use in NHS England is:
Government Data Standards Catalogue: (GDSC), Version 2.0, Agreed 1 January 2002.
Further information can be found on the Cabinet Office website.

This attribute is also known by these names:

Context	Alias
plural	PASSPORT NUMBERS