Suppose my claims recite a "memory" (in the context of a computer arts invention). The novelty of the invention is not in the memory itself.

Next, suppose I define memory in the specification as broadly as anything that "can retain information for subsequent retrieval" (perhaps with some Nuijten exclusions).

It would seem that with such a broad functional definition of memory I am proof to future developments in memory and my claim would be literally infringed even if my novel aspects were combined with a new type of memory not known or practicable at the time of filing.

Suppose on the other hand I list the currently known types of memory in the specification (what one might call a "structural" vs functional definition). Now I would presumably have to rely on DoE to cover combination with new types of memory.

So naturally my question is, are there any pitfalls to giving a functional definition vs a structural one?

1 Answer 1


My first thought is “computer memory” or a similar term would be read as structural in the ordinary meaning. To use it functionally in a means + function manner might be “means for storing binary data”. In that case only listed structures and equivalents would be included.

By the way, “DOE” doesn’t get you what you think it does in M+ function.

the “equivalents” of section 112 (it creates the means + function rules) is not actually the same as the Doctrine of Equivalents (DOE) equivalent. It is a complex area as seen in this quote from PatentlyO -

Means-plus-function claims are interpreted to cover only structures disclosed in the specification that perform the claimed function and, in addition, any equivalents of those disclosed structures. On its face, this appears duplicative of the traditional doctrine of equivalents (DOE). In this case, the Federal Circuit spells out some differences between the two. Most notably, “an equivalent structure [for means-plus-function analysis] under § 112 ¶ 6 must have been available at the time of the issuance of the claim, whereas the doctrine of equivalents can capture after-arising technology developed after the issuance of the patent.” This statement by the court does not, however, precisely explain the distinction. For means-plus-function claims, court precedent allows the doctrine of equivalents to only capture after-arising technology.

I think, in context, just “memory” works. You often see “sensor”, “receiver”, “transmitter”, “fastener” in claims. They are taken to be well understood physical objects, normally with no need of definition.

If in doubt, you can use different ways of including an element in different claims. More structural in one claim and functional in another claim.

In case the way you use “memory” in a claim is seen as functional by a judge you have the advantage of it not being “at the point of novelty”. Even though claims in the US are to taken as a whole, some judges analyses claims into old stuff and new stuff.

  • Maybe I'm missing something, but I don't know what DOE means in this context. Perhaps you might define it.
    – Eric S
    Commented May 8, 2023 at 2:38
  • Thanks @EricS, the multiple ideas of equivalents and the doctrine of equivalents are more complicated than I conveyed so I edited my answer. Beyond my answer there are exceptions to the DOE and exceptions to the exceptions and it is also now barely honored in court now.
    – George White
    Commented May 8, 2023 at 5:41
  • Excellent practical tips in the answer regarding considering not providing a definition at all and claiming things multiple ways. I guess I'm not clear on how "means plus function" interacts with functional definition of a claim term. Up to now I had been assuming these are distinct concepts; MPEP 2111.01(v) seems to explain that a claim term that does not invoke 112(f) can be given a definition in the specification. By default I would not assume that a "memory" invokes 112(f). But it may be that it has to be defined in a way that "connotes structure" to avoid 112(f).
    – bhuff36
    Commented May 8, 2023 at 15:19
  • “a wedge so-shaped as to act as a door stop” is functional claiming in that it doesn’t specify the shape of the wedge other than by a functional property. Alternatively, “means for passively holding open a door” is means + function because it has no structure and by the presumed meaning of “means”. You could cover your bases by using each in a different claim.
    – George White
    Commented May 8, 2023 at 15:37

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