The detailed rules referred to in paragraph 1 shall provide for the opening of annual quotas, if necessary suitably phased over the year, determine the method of administration to be applied and include, where appropriate, provision for: (a) guarantees covering the nature, provenance and origin of the product; (b) recognition of the document used for verifying the guarantees referred to in (a) and (c) the conditions under which import licences are issued and their term of validity.