Under Art. 106(2) EPC (formerly Art. 106(3) EPC 1973) a decision which does not terminate proceedings as regards one of the parties (interlocutory decision) can only be appealed together with the final decision, unless the decision allows a separate appeal. The EPC does not explicitly set out the cases in which interlocutory decisions have to allow a separate appeal. Instead, the legislator has expressly left it to the department making the decision to decide whether to allow an appeal; see the "travaux préparatoires" for the EPC 1973 (T 1954/14). Separate appeal is possible against interlocutory decisions regarding admissibility of the opposition (see e.g. T 10/82, OJ 1983, 407) or maintenance of a patent in amended form (see e.g. T 247/85 and T 89/90, OJ 1992, 456).
In T 857/06 the board stated that a first interlocutory decision which does not allow a separate appeal can be appealed together with a second interlocutory decision which does not leave any substantive issues outstanding and which allows a separate appeal.
The board in T 756/14 observed that allowing a separate appeal against an interlocutory decision under Art. 106(2) EPC is a constitutive decision by the examining decision without which the former decision cannot be challenged by way of an appeal and so this aspect must be included in the order too.