Overview of the steps to be taken for entry into the European phase
The process generally referred to as "entry into the European phase" is not an act in itself but may be described as a series of "steps" to be taken or, in other words, as a bundle of requirements to be fulfilled within 31 months from the international filing date or, where applicable, the earliest priority date claimed for the international application ("31-month time limit"). Which requirements are to be fulfilled within the 31-month time limit depends to a certain extent on the particular case. 
Some requirements must be fulfilled in every case, such as payment of the filing fee (point 534535) and specification of the documents on which processing in the European phase is to be based (points 473474 ff). Further, as a rule, the designation fee is due and the request for examination must be filed at expiry of the 31-month time limit for entry into the European phase, unless the ISR was published extremely late (see points 549550, 590591). However, the filing of a translation, for instance, is required only if the international application was not published in an official language of the EPO (points 509510 ff). This means that for each application the applicant must verify which requirements are to be fulfilled within the 31-month time limit.
If the applicant does not fulfil all requirements that must be met within the 31-month time limit, in many cases - depending on exactly which requirement was not met - the effect is that the application is deemed to be withdrawn as from the date of expiry of that time limit. A loss of rights may be remedied, but only if the strict requirements under which a remedy applies are fulfilled in due time. If not, the application is irreversibly lost. Each of the requirements will be discussed in detail below (see points 447448 ff).
All requirements in respect of which non-timely compliance results in a loss of rights (directly) upon expiry of the 31-month time limit are listed in Rule 159 EPC. In view of that legal effect they are usually referred to as "minimum requirements" for entry into the European phase.

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