What is the format of an international publication number?

The international publication number for PCT applications follows a specific format, as described in PCT Administrative Instructions Section 404:

• It starts with the two-letter code “WO”
• Followed by a four-digit year of publication
• A slant (/)
• A six-digit serial number

For example: “WO 2004/123456”

This number is different from the international application number and is used on the published international application and in the Gazette entry.

To learn more:

• International Publication Number
• PCT
• Patent Numbering