English grammar – states that [a]n article of

a preposition applying to all the members of the series

must either be used only before the first term or else

be repeated before each term.

1) Is one of A, B and C same as: “one of A and one of B and one of c”?

In which case

Valid combinations are: ABC, ABCD Invalid combinations are: AFG, CAJ, AAF

Is "one of A, B and C" same as “any one of A, B and C”? If the above statement is true, then, valid combinations are: “AB, BC, CA, BFG” and invalid combinations are: “AAB, BBH”

Invalid combinations contain multiple occurrence of A, B and C and so they are invalid.

2) One of A, B or C If we go by English grammar rule, then:

Valid are: ABG, CG, ABJ Invalid combinations are: AVY, BCX

3) At least one of A, B and C

Valid combinations are: ABCHJ, BCAKL And invalid combinations are: ABH, BGH, CJK

4)For, "At least one of A, B or C:

Valid combinations are: ABJ, CD, CA Invalid combinations are: ACU, NHB

I am asking this because I have found few references of this is in IPWatchdog. I was still not clear as patent English is quite different in my understanding and I may end up in mess If I follow English grammar but if it can have a different meaning in patent language.

  • Afaik claims are first read in light of the description and only if the description doesn't allow for an interpretation things like dictionaries and grammar are considered. So if the description makes clear which of the above is meant, it doesn't matter what would be correct grammar. Anyways, that's my understanding, correct me if I'm wrong.
    – user18033
    Feb 3, 2017 at 8:52

2 Answers 2


English grammar

First, there is no definitive English grammar. As opposed to other languages which have regulatory bodies, English is wild and lawless. Writers of English grammar books set out what they believe a typical speaker would use, but it is fundamentally nothing more than one writer's opinion.

The standard of interpretation

Notionally, the addressee of the patent is a person having ordinary skill in the art. The meaning of a phrase is what the person having ordinary skill in the art would understanding the patentee to have meant. This may be based on plain English meaning, on the description, on the file history, and any number of other considerations.

What does "one of A, B and C" mean?

This is impossible to answer in the abstract: it depends entirely on the context. Any of the interpretations you suggested might be possible. That is, the phrase might well mean:

  • a single A, a single B, and a single C
  • only A (without B nor C) OR only B (without A or C) OR only C (without A nor B)
  • a single A, one or more Bs, and one or more Cs
  • one or more As, one or more Bs, and one or more Cs

What is the drafter to do?

Make it explicitly clear in your description what you mean. To achieve this, it is common to have a boilerplate paragraph in the description which sets out which interpretations you are using.

It is negligent to hope that the reader will give an ambiguous phrase the meaning you want without anything further, and this is shown repeatedly when poorly drafted patents are litigated.


I don't think you can simply proclaim hard-and-fast, universally applicable rules like this. A patent claim's addressee is a person having ordinary skill in the art, not a layperson or philologist, so inevitably, context will matter, just as the references you cited from IPWatchdog imply.

Another issue concerning "one of A, B, and C" is that the words immediately preceding it will matter, too. Just for example, consider:

"consisting of one of A, B, and C"


"comprising one of A, B, and C"

The former would exclude more than one of A, B, and C being present, while the latter generally wouldn't. See e.g. MPEP 2111.03.

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