Sufficiency of disclosure under Art. 83 EPC requires inter alia that the subject-matter claimed in a European patent application be clearly identified. This requirement must be complied with as from the date of filing because a deficiency in a European patent application as filed, consisting in an insufficient identification of the subject-matter claimed, cannot subsequently be cured without offending against Art. 123(2) EPC which provides that the subject-matter content of a European patent application as filed may not be extended (G 2/93, OJ 1995, 275).
According to the board in T 512/07, objections under Art. 83 EPC 1973 may under some circumstances be overcome by amending the claims, since thereby the "invention" referred to in Art. 83 EPC may be so changed that it no longer depends on the insufficiently disclosed aspects of the application for its realisation. However such objections cannot be overcome by amendment of the description and drawings, since the amendment would then add subject-matter to the application as filed. In general, the claimed subject-matter at issue had to be examined for compliance with Art. 83 EPC 1973 on the basis of the application documents as originally filed.