Why U.S. Patent Claims Usually Avoid Drawing Reference Numerals

Chinese applicants are used to seeing claim language such as “a fastener (12)” or “a control module (100).” When the same application moves to the United States, U.S. counsel often removes the numbers. The reason is easy to misunderstand: U.S. practice does not prohibit reference numerals, and current USPTO guidance says they generally do not affect claim scope. Removing them is usually a drafting and record-management choice, not a rule that Chinese claims were legally defective.

Why the Numbers Look Completely Normal in a Chinese Claim

China's current Implementing Regulations expressly permit a technical feature in a claim to be followed by the corresponding drawing reference sign in parentheses when that helps the reader understand the claim. The same rule also says the reference sign is not to be interpreted as limiting the claim.

That creates a familiar drafting pattern for Chinese applicants. A claim may recite a “base (10),” a “connecting member (20),” and a “driving unit (30),” and the examiner can move quickly between the words and the drawings. The practice is also consistent with the PCT framework. PCT Rule 6.2(b) says that, where drawings exist, claim features should preferably be followed by the relevant reference signs when doing so facilitates quicker understanding, and the signs should preferably be placed in parentheses.

So when a Chinese or PCT application reaches a U.S. practitioner with reference numerals throughout the claims, the document is not inherently malformed. The question is whether keeping those numerals helps the U.S. record.

U.S. Practice Also Permits Reference Numerals

MPEP §608.01(m) is direct on this point. Reference characters corresponding to elements in the description and drawings may be used alongside the same elements in the claims. If used, they should be enclosed in parentheses. The MPEP further states that, generally, the presence or absence of reference characters does not affect claim scope.

That makes one conclusion important: “U.S. patent claims cannot contain drawing numerals” is wrong. An examiner may object if the numerals are presented improperly, but the mere presence of a properly parenthesized numeral is not a reason to reject the claim as such.

The U.S. issue is not a formal ban

If a reference numeral materially improves clarity, U.S. practice allows it. The adaptation question is whether the number adds useful clarity or instead encourages the claim to be read through one illustrated embodiment.

Grit Energy Shows Why a Number Does Not Automatically Narrow the Claim

The Federal Circuit's 2020 decision in Grit Energy Solutions, LLC v. Oren Technologies, LLC is a useful illustration. In an IPR, the Board relied on reference numerals in a prior-art claim together with the corresponding figure to read the claim as disclosing a particular configuration. The Federal Circuit rejected that narrow reading, explaining that the claim's references to those numerals did not limit the disclosure to the illustrated configuration.

The decision fits the broader U.S. principle reflected in the MPEP: reference numerals can aid identification, but they do not ordinarily convert a broadly worded claim term into the exact geometry or configuration shown in one drawing.

That does not mean reference numerals are always harmless in every context. Claim construction depends on the entire intrinsic record—the claim language, specification, and prosecution history. A number does not override that analysis, but an unnecessary visual pointer can still create avoidable argument about what the drafter meant.

Why U.S. Practitioners Often Remove Them Anyway

The strongest reason is drafting discipline. A U.S. claim is expected to define the protected subject matter in words. If “fastener” is the intended limitation, the claim should stand on that word and the intrinsic definition around it. Adding “(12)” may encourage the reader to jump immediately to the one drawing where item 12 happens to be a screw, even though “fastener” was intended to cover screws, clips, latches, or another supported structure.

This visual anchoring is not a separate doctrine of U.S. patent law, and it should not be exaggerated into one. It is a practical communication risk. Patent prosecutors, judges, technical experts, jurors, and business teams all read claims alongside figures. If a number contributes no real clarity, removing it leaves fewer invitations to confuse the claim term with a single embodiment.

There is also a consistency problem. In a long Chinese application, the same reference number may have been revised in the drawings but not every claim; or the English translation may change the noun attached to a number. A number that was meant to clarify can then become evidence of an internal mismatch. U.S. adaptation often removes that unnecessary layer before it creates prosecution work.

PCT Habit Is Not the Same as U.S. National-Phase Strategy

PCT Rule 6.2(b) expressly favors reference signs when they speed understanding, while U.S. practice permits them without requiring them. That difference is a good example of why a PCT-compliant claim should not automatically be treated as a finished U.S. claim.

The same application can therefore use reference signs legitimately in the international phase and later remove them for U.S. prosecution. Nothing inconsistent has happened. The drafting objective has changed from creating a broadly intelligible international claim to managing a U.S. examination and enforcement record.

A Practical Rule for China-to-U.S. Adaptation

Do not remove reference numerals because you think U.S. law forbids them; it does not.
Keep them only when they materially improve understanding of a technically complex claim.
If retained, place them in parentheses and confirm complete consistency with the description and drawings.
Never use a numeral as a substitute for claim language that should define the structure or relationship in words.
Check whether the associated drawing depicts only one embodiment of a broader supported term.
For a U.S. filing, ask whether each numeral adds legal-technical clarity or merely carries over a Chinese/PCT drafting habit.

Takeaway

Reference numerals are a small drafting detail, but they capture the larger point of cross-border adaptation. A Chinese drafting convention can be completely legitimate at CNIPA and completely permissible at the USPTO, yet still be worth changing because the U.S. record will be read and used differently.

The better question is therefore not “Are reference numerals allowed in U.S. claims?” They are. The better question is “What does this numeral contribute to the U.S. claim?” If the answer is nothing beyond pointing the reader back to one drawing, removing it is often the cleaner choice.