37 C.F.R. § 2.85 : Patents, Trademarks, and Copyrights — UNITED STATES PATENT AND TRADEMARK OFFICE, DEPARTMENT OF COMMERCE — GENERAL — RULES OF PRACTICE IN TRADEMARK CASES —CLASSIFICATION — Classification schedules

(a) International classification system. Section 6.1 of this chapter sets forth the international system of classification for goods and services, which applies for all statutory purposes to:
(1) Applications filed in the Office on or after September 1, 1973, and resulting registrations; and
(2) Registrations resulting from applications filed on or before August 31, 1973, that have been amended to adopt international classification pursuant to §2.85(e)(3).
(b) Prior United States classification system. Section 6.2 of this chapter sets forth the prior United States system of classification for goods and services, which applies for all statutory purposes to registrations resulting from applications filed on or before August 31, 1973, unless:
(1) The registration has been amended to adopt international classification pursuant to §2.85(e)(3); or
(2) The registration was issued under a classification system prior to that set forth in §6.2.
(c) Certification marks and collective membership marks. Sections 6.3 and 6.4 specify the system of classification which applies to certification marks and collective membership marks in applications based on sections 1 and 44 of the Act, and to registrations resulting from applications based on sections 1 and 44. These sections do not apply to applications under section 66(a) or to registered extensions of protection.
(d) Section 66(a) applications and registered extensions of protection. In an application under section 66(a) of the Act or registered extension of protection, the classification cannot be changed from the classification assigned by the International Bureau of the World Intellectual Property Organization, unless the International Bureau corrects the classification. Classes cannot be added, and goods or services cannot be transferred from one class to another in a multiple-class application.
(e) Changes to Nice Agreement. The international classification system changes periodically, pursuant to the Nice Agreement Concerning the International Classification of Goods and Services for the Purposes of the Registration of Marks. These changes are listed in the International Classification of Goods and Services for the Purposes of the Registration of Marks, which is published by the World Intellectual Property Organization.
(1) If international classification changes pursuant to the Nice Agreement, the new classification applies only to applications filed on or after the effective date of the change.
(2) In a section 1 or section 44 application filed before the effective date of a change to the Nice Agreement, the applicant may amend the application to comply with the requirements of the current edition. The applicant must comply with the current edition for all goods or services identified in the application. The applicant must pay the fees for any added class(es).
(3) In a registration resulting from a section 1 or section 44 application that was filed before the effective date of a change to the Nice Agreement, the owner may amend the registration to comply with the requirements of the current edition. The owner must reclassify all goods or services identified in the registration to the current edition. The owner must pay the fee required by §2.6 for amendments under section 7 of the Act. The owner may reclassify registrations from multiple United States classes (§2.85(b)) into a single international classification, where appropriate.
(f) Classification schedules shall not limit or extend the applicant's rights, except that in a section 66(a) application, the scope of the identification of goods or services for purposes of permissible amendments ( see§2.71(a)) is limited by the class, pursuant to §2.85(d).

37 C.F.R. §2.85

73 FR 67770, 11/17/2008