As has been stated in G 2/98 (OJ 2001, 413), the extent of the right to priority is determined by, and at the same time limited to, what is disclosed in the priority application.
In T 923/00 the application as filed and the priority document were in essence identical. The board emphasised that any conclusion in favour of or against the amendments' allowability under Art. 123(2) EPC 1973 would also apply in favour of or against entitlement to the claimed priority, and dealt with both issues jointly.
In G 1/03 and G 2/03 (OJ 2004, 413 and 448) the Enlarged Board held that in order to avoid any inconsistencies, the disclosure as the basis for the right to priority under Art. 87(1) EPC 1973 and as the basis for amendments in an application under Art. 123(2) EPC 1973 had to be interpreted in the same way (see also G 2/10, OJ 2012, 376). That meant that a disclaimer, not providing a technical contribution as outlined, which was allowable during the prosecution of a European patent application did not change the identity of the invention within the meaning of Art. 87(1) EPC 1973. Therefore its introduction was allowable also when drafting and filing the European patent application without affecting the right to priority from the first application, which did not contain the disclaimer (see also T 175/03 and T 910/03; further, T 680/08).