The act of testing is based on the fundamental premise on freedom in drawing up a will. The basis for the recognition of a will is valid while the use of appropriate, specified by law, the forms of the same act. The principle of favor testamenti but it permits the possibility of recognizing forms of theory are considered inappropriate or not complying with the law, because of the freedom of testing, as well as the duty to realize and respect the last will of the deceased. Is thus permissible to adopt a will in the form of a letter, the will combined, including the will of the two heirs and other forms of wills, in the case where the testator was not able to make a will the ordinary. Favor testamenti also gives ground to the correct interpretation of the will of the deceased when the members of the immediate family were not counted in the will, and one of the criterion of interpretation becomes the absence of a right to a reserved portion of the deceased.