The parties, witnesses and experts to be heard must be invited to appear to give evidence on the date fixed. The summons must be notified. At least two months' notice of a summons issued to a party, witness or expert to give evidence must be given, unless they agree to a shorter period. The summons must contain:
(i)an extract from the order to take evidence, indicating in particular the date, time and place of the investigation ordered, whether it will be conducted by videoconference and stating the facts regarding which parties, witnesses and experts are to be heard;
(iv)an indication that any party, witness or expert may request to be heard by the competent court of their country of residence and a requirement that they inform the EPO within a time limit to be fixed by the EPO whether they are prepared to appear before it (see E‑IV, 3.2.2 (iii) and E‑IV, 3.2.2 (iv)).