37 CFR § 2.65 - Abandonment.
(a) An application will be abandoned if an applicant fails to respond to an Office action, or to respond completely, within six months from the date of issuance. A timely petition to the Director pursuant to §§ 2.63(a) and (b) and 2.146 or notice of appeal to the Trademark Trial and Appeal Board pursuant to § 2.142, if appropriate, is a response that avoids abandonment (see § 2.63(b)(4)).
(1) If all refusals and/or requirements are expressly limited to certain goods and/or services, the application will be abandoned only as to those goods and/or services.
(2) When a timely response by the applicant is a bona fide attempt to advance the examination of the application and is a substantially complete response to the examining attorney's action, but consideration of some matter or compliance with a requirement has been omitted, the examining attorney may grant the applicant thirty days, or to the end of the response period set forth in the action to which the substantially complete response was submitted, whichever is longer, to explain and supply the omission before the examining attorney considers the question of abandonment.
(b) An application will be abandoned if an applicant expressly abandons the application pursuant to § 2.68.
(c) An application will be abandoned if an applicant in an application under section 1(b) of the Act fails to timely file either a statement of use under § 2.88 or a request for an extension of time for filing a statement of use under § 2.89.