(a) A will shall be in writing and shall be signed by the testator or by some other individual in the testator's presence and at the testator's express direction. A testator may sign by mark or by any name that is intended to authenticate the instrument as the testator's will.

(b) A will shall be attested and subscribed in the presence of the testator by two or more competent witnesses. A witness to a will may attest by mark. Another individual may not subscribe the name of a witness, even in that witness's presence and at that witness's direction.

(c) A codicil shall be executed by the testator and attested and subscribed by witnesses with the same formality as a will.