"Multiple priorities may be claimed" – i.e. a European application may claim rights of priority based on more than one previous application. The previous application may have been filed in or for the same or different states or members of the WTO, but in all cases the earliest application must have been filed not more than 12 months before the date of filing of the European application. Subject-matter of a European application will be accorded the priority date of the earliest priority application which discloses it. If, for instance, the European application describes and claims two embodiments (A and B) of an invention, A being disclosed in a French application and B in a German application, both filed within the preceding 12 months, the priority dates of both the French and German applications may be claimed for the appropriate parts of the European application; embodiment A will have the French priority date and embodiment B the German priority date as effective dates. If embodiments A and B are claimed as alternatives in one claim, these alternatives will likewise have the different priority dates as effective dates.
According to G 1/15, entitlement to partial priority may not be refused for a claim encompassing alternative subject-matter by virtue of one or more generic expressions or otherwise (generic "OR"-claim) provided that said alternative subject-matter has been disclosed for the first time, directly, or at least implicitly, unambiguously and in an enabling manner in the priority document. No other substantive conditions or limitations apply in this respect.
If, on the other hand, a European application is based on one previous application disclosing a feature C and a second previous application disclosing a feature D, neither disclosing the combination of C and D, a claim to that combination will be entitled only to the date of filing of the European application itself. In other words, it is not permitted to "mosaic" priority documents. An exception might arise where one priority document contains a reference to the other and explicitly states that features from the two documents can be combined in a particular manner.