B. The international and European phases of a PCT application 

¹ RO = Receiving Office

² ISA = International Searching Authority (to be specified by the RO and, where applicable, chosen by the applicant)

³ SISA = Supplementary International Searching Authority

⁴ IPEA = International Preliminary Examining Authority
(as for ISA; EPO only when ISA = EPO or XN or XV or AT, ES, FI, SE, TR patent office) 

⁵ As from date of filling or earliest date of priority. The 31 month limit applies for entry into the European phase (before the EPO as designated Office (Ch. I) and elected Office (Ch. II)).

⁶ Currently one extension state: BA.

⁷ Currently four validation states: MA, TN, MD and KH.