As soon as one serves a summons, therefore, prescription is interrupted. Acquisitive prescription describes the acquisition of property, or rights of ownership, and therefore falls outside the scope of contract law. Contractual rights and duties are generally transmissible on death, although not in the case of a "delectus personae" or an express or tacit agreement to the contrary, in which case resolution of the contract is left to the executor of the deceased's estate. The contracting parties’ main objective during contract negotiation should be to reach a consensus regarding the exact object of their agreement on the best commercial terms and conditions. To be valid, certain contracts must be notarially executed, e.g. antenuptial or prospecting agreements and mining leases, in which case they are called ‘deeds’ and are public instruments. It is vital to first identify the type of undertaking and describe the contracting parties. The parties and their contact details should be properly described in the contract document. The agreement's nature depends on its contents. When the contract is nominate, care must be taken to include the "essentialia" for that agreement in the contract. Following the commencement should come clauses setting out the "causa" of the contract, its object and the extent of the parties’ obligations, much of which is typically found in the recitals. The contract should be properly signed and dated to be effective. The contract may be dated in the introductory or execution clauses. The contract should be structured in a logical and practical fashion. After the commencement, recitals and the definitions and interpretation clause, the operative provisions should appear. First come core provisions that set out the undertakings and primary obligations specifically negotiated by the parties for their contractual relationship, such as clauses on the remedies for breach of contract, including cancellation, penalty, forfeiture, limitation and exemption clauses; and conditions and time periods. Then follow general clauses on variation, severability, entire agreement, cession, waiver, "domicilium citandi et executandi" (notices, address for service), applicable law and jurisdiction, alternative dispute resolution procedures, force majeure ("vis major" and "casus fortuitus"), costs, and confidentiality. Lastly, principles of good language and grammar, and proper numbering, should be used throughout.