Civil legislation, without prejudice to the preservation, modification and development by the Self-governing Communities of their civil law, foral or special, whenever these exist, and traditional charts. In any event rules for the application and effectiveness of legal provisions, civil relations arising from the forms of marriage, keeping of records and drawing up to public instruments, bases of contractual liability, rules for resolving conflicts of law and determination of the sources of law in conformity, in this last case, with the rules of traditional charts or with those of foral or special laws.