If there is no applicable act for a civil case, the case shall be decided according to customs. If there is no such custom, the case shall be decided according to the jurisprudence.

Only those customs which are not against public policy or morals shall be applied to a civil case.

While a written document is required by the act, it is unnecessary written by the person himself, but it must be signed by him.
If the person uses a seal in stead of his signature, the affixing of such seal has the same effect as of his signature.
The effect of a finger-print, cross or other mark will be equivalent to the effect of a signature provided that it is certified with two witnesses' signatures.

If a certain quantity is expressed both in characters and in figures, and if there is inconsistency between them, the expression in characters shall be governed when the court cannot ascertain the real intent of the parties.

If a certain quantity is expressed in characters or in figures more than once, and if there is inconsistency in them, the fewest shall be governed when the court cannot ascertain the real intent of the parties.