Where the competent department of the EPO considers it necessary to hear the oral evidence of parties, witnesses or experts or to carry out an inspection, it must make a decision to this end (order to take evidence), setting out the investigation which it intends to carry out, relevant facts to be proved and the date, time and place of the investigation. If oral evidence of witnesses and experts is requested by a party but the witnesses and experts are not simultaneously named, the party is requested, either prior to the issue of the order to take evidence or in the order itself, to make known within a specified time limit the names and addresses of the witnesses and experts whom it wishes to be heard. The time limit to be computed in accordance with Rule 132(2) will be not less than two months and not more than four months, since the party concerned will normally know beforehand whom he wishes to be heard as a witness or expert.

The order to take evidence must be notified to the parties. It may be appealed only together with the final decision, unless it allows separate appeal (see X, 6).