ANNEXSupplementary provisions
Article 164 of the postal services Regulation adopted by Decree No 1653/1964 of 14 May 1964 (BOE of 9 June 1964), as amended by the Ministeral Decree of 12 July 1966 (BOE of 23 July 1966). 1. A letter is any sealed consignment the content of which is not indicated and cannot be seen, and all writings of an immediate and personal nature, even if they are visible. 2. The following in particular are regarded as letters: business records, either fully or partially completed, estimates, passenger waybills, invoices, signed bills of exchange, transfer notices, receipts, detailed accounts and their supporting documents, other commercial documents, insurance documents; acts, certificates and various files; public or private acts or instruments and copies thereof; criminal and civil papers, delayed letters or post-cards; chess problems, betting and competition documents; land register, vehicle register and census documents and other similar papers. 3. The following are not considered to be letters even if sealed: small parcels, parcel post consignments, post-cards even if of an immediate and personal nature. Nor are consignments specifically given another classification by the Post Office regarded as letters, even if they satisfy the definition given in point 1 above.