In T 896/92 the board emphasised that, in accordance with T 169/83 (OJ 1985, 193), further conditions were required as to the disclosure of a feature shown solely in a drawing. In this respect, not only should the structure of the feature be shown sufficiently clearly in the drawing, but also the technical function achieved should be derivable (see also T 241/88).
In T 204/83 (OJ 1985, 310) the board held that features shown solely in a drawing formed part of the state of the art when a person skilled in that art was able, in the absence of any other description, to derive a technical teaching from them. Dimensions obtained merely by measuring a diagrammatic representation in a document did not, however, form part of the disclosure (see T 857/91, T 272/92, T 1488/10, T 1943/15).
In T 451/88 the distinction was drawn between scaled construction drawings and the schematic drawings conventionally included in patent documents, the latter being sufficient to indicate the essential elements of the invention but not to manufacture the product. It was found that schematic drawings could not be used to derive a ratio between two dimensions (T 1664/06).
In T 56/87 (OJ 1990, 188) the board held that a technical feature which was derived from or based on dimensions obtained from a diagrammatic representation and which technically contradicted the teaching of the description, did not form part of the disclosure of a document.
T 748/91 was concerned with measuring relative dimensions in drawings. In that case the board found that size ratios could, under certain circumstances, be inferred even from a schematic drawing.
In T 2052/14, the board observed that, even though the examining division had had the impression that drawings in a prior-art document showed the feature in the characterising portion of claim 1, that did not amount to a direct and unambiguous disclosure for the skilled person, who would know that those drawings were merely schematic views from which, in the absence of any specifications, no specific sizes or proportions could be derived. Since the drawings at issue were not marked as true to scale, they could only be standard schematic views.
In T 141/16 the board found that although the figures of the prior art document E4 were merely schematic and no measurements could therefore be directly taken from such drawings, some information could be unambiguously derived fro them. However, figure 3 of the prior art document E4 represented a clear and unambiguous disclosure of a particular angle, in the sense that the components were shown "slanted".