In T 332/87 a dated internal paper, marked as being confidential and not signed, was - together with an undated leaflet - not considered sufficient evidence. In T 595/89 the board decided that the opponent's in-house documents relating to the installation of a device in an aeroplane and to the sale thereof were not sufficient to prove public prior use.
In T 204/88 a letter of tender was not sufficient to prove public prior use because it was not discernible when and to whom the device was to be delivered and because the device was described in terms too general for anyone to identify whether it corresponded to the invention. In T 725/89 too, a dated tender was not regarded as sufficient evidence, as it was not proven when the tender had actually been presented, and the date of the tender was only one week prior to the priority date. By contrast, the board took the view in T 482/89 (OJ 1992, 646) that an unsigned delivery note, together with other documents, could constitute sufficient evidence of delivery.
In T 48/96 the board decided not to accept copies of pages from a catalogue bearing a date as sufficient proof of availability to the public. In order to prove the allegation that a particular apparatus described in a catalogue had been available to the public before the priority date, it was not sufficient to show that the catalogue had been published on time, because a mere indication in a catalogue did not constitute absolute proof that the described product had in fact been available to anybody; for example, there could have been a delay.
In T 905/94 the patent proprietor had exhibited a blind at an exhibition. After having considered the evidence regarding the exhibition the board looked at the question of whether use of the same trade name for different models could constitute evidence of the fact that the patent proprietor had marketed or described the blinds according to the patent at issue before the date of priority. In the board's opinion, such use could not constitute sufficient evidence since it was common practice in industry for the same name to be used and retained for a product, the technical characteristics of which changed over time as improvements were made.