Patent numbers.

Two elements -- the country code (two letters) and the serial number (one to twelve digits).

And sometimes a "kind code" at the end

Application numbers.

Three pieces -- the country code (two letters), the filling year (four digits) and a serial number (up to seven digits)

And sometimes "other information" sandwiched between the year and serial number

Common Country Codes include:

US -- United States

EP -- European Patnt

WO -- World Trademark Office (ok NOT a country)

DE -- Germany

CN -- China

JP -- Japan

CA -- Canada

Kind Codes are general added to the end of a patent or patent application number. They provide additional information on the status of the application or patent. They are usually 1 or 2 digits with the first digit being a letter. Patent applications are general "A" documents. Patents are "B" documents. Each country has different kind codes.

U.S. Kind Codes (used until 2001)

A    PATENT
P    PLANT PATENTS [up TO 11727]
S    DESIGN PATENT

U.S. Kind Codes (used after 2001)

A              GRANTED PATENT 
A1            FIRST PATENT APPL.
A2            REPUBLISHED PATENT APPL.
A9            CORRECTED PATENT APPL.
B1 - B3     REEXAM. CERTIF.
C1-C9      REEXAMINATION
S1            DESIGN PATENT

U.S. Kind Codes for Plant Patents

P1   FIRST PUBL. APPL.
P2    FIRST PUBL. GRANTED
P3    SECOND PUBL. GRANTED
P4    REPUBLISHED APPL.
P9    CORRECTED APPL.