The international application must contain "one or more claims."[Art. 3(2); Art. 6; GL/ISPE 5.01; 5.02; ]

The claims must:

This chapter sets out the appropriate form and content of the claims, together with how they should be interpreted for the purposes of assessing the novelty and inventive step of the inventions which they define and searching for prior art which may be relevant to making that assessment.

For form-filling of the written opinion in case of formal defects or of clarity, conciseness or support issues, see GL/PCT‑EPO B‑XI, 3.2.4.