If the applicant has omitted to file with the international application a part of the description or of the claims, part or all of the drawings or an entire element, i.e. the entire description or all the claims, the omission may be incorporated in the international application by reference.
Firstly, the omission must be completely contained in an application from which priority was claimed on the international filing date. For an omission to be "completely contained", it must be identical to the corresponding text/drawing in the priority document.
Secondly, the PCT request must have contained a statement of incorporation by reference to the priority application. A statement to that effect is already provided for in Box VI of the PCT request form (PCT/RO/101).
If all the conditions are met, the omission is considered to be incorporated by reference and the international filing date is unaffected.
If the description and/or claims as contained in the priority application do not qualify as missing parts on the grounds that the international application already contained a complete description and/or a complete set of claims, the EPO as receiving Office will proceed to a negative finding under GL/RO paragraph 205D and will not transmit the international application to the IB in accordance with Rule 19.4(a)(iii).
An applicant wishing to add to an international application omitted parts which have no basis in a priority application may do so under Rule 20.5. However, the filing date of the application as a whole will then be the date on which the missing parts are filed.