In my experience very few US patent documents have reference numbers in the claims or abstract, even though doing so would make the document easier to understand. Why is this?

MPEP 608.01(m) states:

Generally, the presence or absence of such reference characters does not affect the scope of a claim.

I understand that the MPEP is just USPTO policy during examination and not law, but it would seem odd to me for the claim scope to be treated dramatically differently during litigation. So for claims at least, why not include reference numbers? They seem common in other jurisdictions. Many practitioners seem paranoid about possibly accidentally narrowing the interpretation of claims, and in my view overreact in ways that make the document harder to understand. My guess is that not including reference numbers in claims is an example of this.

I haven't found anything in the MPEP about reference numbers in the abstract aside from that reference numbers are expected in the abstracts of PCT applications:


(E) Reference numbers of the main technical features placed between parentheses.

1 Answer 1


In most of the world reference numbers are required in the claims and encouraged in the abstract. Reference numbers in claims are rarely seen in U.S. patents.

It is not overly paranoid to think a judge or jury will fix on a concrete, labeled, drawing item in a specific embodiment as defining an element in a claim. Specifications and drawings depict specific embodiments but claims cover a scope of embodiments. If a claim element is “a fastener” and the drawing of an embodiment shows a screw and “fastener” is followed by a reference number pointing to a screw it will not be surprising that a juror will, unconsciously or not, think only screws are fasteners.

If you find it easier to read a claim with reference numbers then I submit your view of the claim is overly influenced by the embodiment. I find numbers interspersed in a claim to break my thoughts as I try to comprehend the claim.

  • Thanks, I had not considered that a jury could be responsible for claim interpretation.
    – Ignoramus
    Commented Jan 4, 2022 at 3:00
  • Technically claim interpretation is considered a mixed question of law and facts and is determined by judges but a claim that jurors understand is a plus.
    – George White
    Commented Jan 4, 2022 at 3:03

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