Which application type is allowed to be faxed to the USPTO?

The correct answer focuses on the specific type of application that is permitted to be submitted via fax to the USPTO. A continuation application filed pursuant to 37 CFR 1.53(d) is explicitly recognized by the USPTO as an application type that can be transmitted by fax. This is due to the specific allowances made for certain filings that cater to expedited processing or situations where immediate filing is necessary.

In contrast, non-provisional and provisional applications typically require submission through more traditional routes like electronic filing or mailing, as the USPTO has established guidelines that prioritize the completeness and accuracy of such applications. Additionally, national stage applications, which arise from international patent applications under the Patent Cooperation Treaty (PCT), also adhere to stricter filing requirements that do not include fax submissions.

Thus, the rules laid out under 37 CFR 1.53(d) create a clear pathway for faxing continuation applications, while other application types do not hold the same privilege. This highlights the USPTO’s approach to ensuring that particular categories of applications have streamlined processes for urgent or necessary filings through fax.