Article 7 — Formal requirements
An interest is constituted as an international interest under this Convention where the agreement creating or providing for the interest:
(a) is in writing;
(b) relates to an object of which the chargor, conditional seller or lessor has power to dispose;
(c) enables the object to be identified in conformity with the Protocol; and
(d) in the case of a security agreement, enables the secured obligations to be determined, but without the need to state a sum or maximum sum secured.