CASELAW-EPO - reviews of EPO Boards of Appeal decisions

T 950/20 – Features in brackets/parentheses in a claim – Limiting or not?

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The patent relates to a “Coriolis mass flow measuring device”

Brief outline of the case

The opposition was rejected and the opponent appealed.

In appeal, the opponent requested revocation.

In appeal, the proprietor requested rejection of the opposition or maintenance according an AR.

The board decided revocation of the patent for lack of IS.

The board held that claim 1 as granted lacked IS over E3=WO 96/08697 (1st A in ESR) + E5=WO 2006/010687 (not in the ESR).

Claim 1 as granted comprised symbols in brackets “(R1)”, “(R2)” and “(R1, R2)”, see below.  

The same objection of lack of IS applied to AR1 in which only the brackets in the terms “(R1)”, “(R2)” and “(R1, R2)” were deleted.

The claim at stake

Coriolis mass flowmeter (1) with at least four bent measuring tubes (2a, 2b, 2c, 2d), at least one actuator assembly and at least one sensor assembly, wherein ………, and wherein the geometry and/or the surface characteristics of the measuring tubes (2a, 2b, 2c, 2d) have been set in such a manner that the tube flow resistance of all four measuring tubes (2a, 2b, 2c, 2d) is identical,

characterized in that

the bending radii (R1, R2) of the measuring tubes (2a, 2b; 2c, 2d) located in each of the common planes (E1, E2) ……, that the first measuring tube (2a) and the fourth measuring tube (2d) begin with an archshaped portion with the radius (R2), then two archshaped portions with the radius (R1) follow and finally there is an arch shape with the radius (R2), and that the second measuring tube (2b) and the third measuring tube (2c) begin with an arch-shaped portion with the radius (R1), then two arch-shaped portions with the radius (R2) follow and finally there is an archshaped portion with the radius (R1).

The symbols in brackets

The references in brackets (2a, 2b, 2c, 2d) are clearly to reference signs relating to the drawings. According to R 43(7), reference signs are not considered limiting the claim.

The question to be answered here is whether the terms in brackets “(R1)”, “(R2)” and “(R1, R2)” are limiting although they are in brackets in the claim.

In a given characteristic, i.e. M 10, the terms “the radius (R1)” and “the radius (R2)” are used to designate two different radii.

If the symbols “(R1)” and “(R2)” in brackets were omitted as reference signs for the interpretation of characteristic M10, it would be unclear to which radius the respective phrase “the radius” refers.

The board agreed with the OD that expressions in brackets in a claim are not necessarily to be interpreted as reference signs within the meaning of R 43(7) and as such should not have any restrictive effect under that provision.

The board held that if it is unclear whether such bracket terms are actually reference signs or not, this must be clarified by interpreting the claim, whereby a technically reasonable interpretation must be chosen.

In this context, the OD and the patent proprietor rightly stated that feature M10 would not make any technical sense if the symbols in brackets “(R1)”, “(R2)” and “(R1, R2)” were to be understood as mere reference signs, so that they could also be omitted altogether.

For the board, the OD correctly stated that, if the bracketed radii were omitted, “[t]he references to ‘the radius’ (…) are unclear [because] no single specific radius has been predefined“. This ambiguity is particularly obvious since there must be several (i.e. at least two) bending radii and it remains open to which of these bending radii the ‘the radius’ refers in each case”.

The Board considered that the symbols in brackets “(R1)”, “(R2)” and “(R1, R2)” have a restrictive effect consisting in designating two different radii R1 and R2.

With this interpretation in mind, the board came to the conclusion that claim 1 as granted lacked IS over E3 + E5. As only the brackets were removed in AR1, it was as well lacking IS.

An interesting older decision

T 1481/05, relates to “A method of and an implement for automatically milking animals”.

Deletion of the features in brackets

Claim 1 of the MR (=as granted) differed from claim 1 as filed in that the definitions of the terms “pulse milk flow” and “suction phase”, which were enclosed in parentheses in claim 1 as originally filed, have been deleted:

(i) “By pulse milk flow it is meant the milk flow from a teat during a single suction phase of the milking process”.

(ii) “By suction phase it is meant the time during which the teat is exposed to a vacuum during the previously mentioned pulse milk flow”.

The board held that the deletion of the sentences i) and ii) in brackets infringed Art 123(2), so that the MR was not allowable.

Features in brackets

The above sentences i) and ii) were reintroduced in each of independent claims 1 and 10 of the first AR.

The question arose whether the use of parentheses in the claims is admissible at all. According to R 29(1) EPC73, now R 43(1), the claims should define the matter for which protection is sought in terms of technical features of the invention.

R 43 EPC2000 corresponds exactly to R 29(1) EPC1973. In the following only R 43 will be mentioned.

The board considered that, that according R 43(6), first sentence, technical features references may only be made to the description or the drawings insofar as this is absolutely necessary. Rule 43(7) mentions the possible use of parentheses in connection with reference signs, but otherwise the EPC is silent about the possibility to use parentheses in the claims in general, and thus there appears to be no explicit prohibition against their use.

For the board, the problem arose from the fact that in standard language, parentheses may be used for widely varying purposes, where the semantic role of the parentheses can often only be inferred from the context of use.

In general, the reader can never be quite certain of the intended meaning. In other words, the use of parentheses by itself introduces some level of ambiguity in any text, patent claims being no exception.

Therefore, as a rule, the use of parentheses in claims should be avoided, apart from the well-established use with reference signs or their standard uses in the relevant technology.

For the board, the parentheses thus introduced an ambiguity as to the content of the claimed subject-matter. AR1 was not allowable for this reason.

Brackets deleted

Compared with claims 1 and 10 of AR1, claims 1 and 10 of AR 2 have in essence been amended by deleting the parentheses, so that the above mentioned lack of clarity no longer applies.

For the board, the definitions i) and ii) cannot be considered as “abandoned” matter and their re-introduction into the claims of AR2 does not extend the protection conferred with respect to that of the patent as granted under Art 123(2). Moreover, the board held that the deletion of the parentheses does not contravene Art 123(2).

Following remittal, the patent was maintained in amended form by the OD.


In view of those two decisions, brackets in a claim should imperatively be reserved to reference signs relating to the figures.

Any statement in brackets, other than reference signs, introduced in a claim renders the claim unclear, as it is not apparent whether the statement in brackets is limiting or not.

If the statements in brackets are deleted, the deletion is considered as introducing added matter.

The only way to avoid problems of lack of clarity or of added matter for symbols/sentences other than reference signs relating to the figures, is to keep the features in brackets but to delete the brackets/parenthesises in the claim.

In T 950/20 the symbols in brackets “(R1)”, “(R2)” and “(R1, R2)” were manifestly representing technical features of the claims. In view of T 1481/20, it was thus only necessary to read the claim without the brackets.

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