As you know, the EPO has quite strict rules regarding corrections. In particular, corrections will not be allowed unless it is immediately evident to the skilled person that an error has occurred and how it should be corrected. Sometimes, as in the present case, opponents push this reasoning too far.
The patent proprietor wished to amend its claims by introducing a temperature (72°F) which it said was disclosed in paragraph  of the patent. However, this paragraph only contained a reference to a value 72EF:
[1.2.2] [The opponent] admits that a skilled reader will realise that “72EF” in paragraph  of the description is an obvious error, but contests that “72°F (22.2°C)” now introduced in claim 1 of auxiliary request 1 is the only possible correction. It considers that instead of the temperature the correction could for instance concern the pressure or any other parameter the skilled person could think of in the technical field of testing moisture ingress of containers. Therefore, the correction would not be admissible as it clearly contravenes Rule 139 and Article 123(2) EPC.
The Board, however, shares [the patent proprietor’s] view that the only possible correction having a technical meaning in the present context is the temperature as it is an essential parameter for such a test. This appears clearly for instance from D10, 1st page, top of right-hand column […]. Consequently, the skilled person will immediately consider that “F” means “Fahrenheit” and make the correction accordingly. Hence, the correction complies with R 139 and A 123(2).
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