T 963/08 – Substantially Unclear

When drafting claims, one is sometimes tempted to insert expressions such as “substantially” in order to allow for some margin. However, there is a real risk of making the claims unclear by using such expressions, as the present case illustrates.

The Board had to deal with an appeal against the decision of the Examining Division (ED) to refuse an application. Having found the main request before it to lack inventive step, the Board examines the first auxiliary request, claim 1 of which read:

A method comprising:

• precoding a plurality of symbol vectors (I) using a linear complex field matrix that comprises a square complex field matrix having substantially a row-wise Vandermonde structure to produce precoded symbol vectors, each symbol vector comprising a plurality of symbols (203), the plurality of symbols (203) being modulation symbols (203);
• grouping the precoded symbol vectors into two or more groups (209) respectively comprising a plurality of layers (207) of precoded symbol (203) vectors;
• applying power coefficients to each modulation symbol within the groups (209) of layers (207), wherein the power coefficients are arranged to produce unequal power allocations among at least a subset of the layers (207);
• mapping the precoded modulation symbols (203) of the precoded symbol vectors to respective subcarriers of a plurality of subcarriers of a multicarrier communication channel and to respective spatial channels of a plurality of spatial channels based on a precoded modulation symbol’s group and a precoded modulation symbol’s layer.

The Board raised a clarity objection that had already been made by the ED:

[4] The subject-matter of claim 1 of this request is distinguished from that of the main request by further specifying that the plurality of symbols are modulation symbols and that for pre-coding a linear complex field matrix is used that comprises a square complex field matrix having substantially a row-wise Vandermonde structure.

[4.1] Regarding the use of a linear complex field matrix, by using the term “substantially” the problem under A 84 as argued in […] the decision under appeal persists. The appellant addresses this objection merely by alleging that such a relative term “would be clearly understood by the skilled person”, without giving reasons why.

[4.2] The only information found in the description is that a Vandermonde matrix is a type of matrix that arises in the polynomial least squares fitting, Lagrange interpolating polynomials and the reconstruction of a statistical distribution from the distribution’s moments […].

A Vandermonde matrix of order n in general is in the form:

The solution of an n x n Vandermonde matrix equation requires O(n²) operations. The determinants of Vandermonde matrices have a particularly simple form.

The board would like to note that a special Vandermonde matrix is the discrete Fourier transform matrix.

Regarding the use of a Vandermonde matrix in the context of the invention, the application only uses the expression “substantially row-wise Vandermonde structure” several times, without disclosing how such a matrix is used for the invention.

[4] The ED presented a concrete argument by raising the question whether a “substantially” row-wise Vandermonde structure encompassed a true Vandermonde matrix or not. The appellant failed to address this argument.

The mere reference of the appellant to decision T 378/02 is not a convincing counter-argument. In the afore-mentioned decision it was ruled that relative terms in claims are allowable if they are clear in view of the complete specification. This, however, is not the case for the present application, because the application as filed fails to provide any explanation as to what is to be understood by a “substantially” row-wise Vandermonde structure.

The board therefore agrees with the reasoning of the ED regarding the term “substantially” and maintains the objection under A 84.

So when you use the “substantially” language in your claims, make sure that the description explains what is meant and, if possible, provide a definition that could be inserted into the claim, should the ED require you to do so.

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