Sec. 17. Construction where instrument is ambiguous. - Where the language of the instrument is ambiguous or there are omissions therein, the following rules of construction apply:(a) Where the sum payable is expressed in words and also in figures and there is a discrepancy between the two, the sum denoted by the words is the sum payable; but if the words are ambiguous or uncertain, reference may be had to the figures to fix the amount;
(b) Where the instrument provides for the payment of interest, without specifying the date from which interest is to run, the interest runs from the date of the instrument, and if the instrument is undated, from the issue thereof;
(c) Where the instrument is not dated, it will be considered to be dated as of the time it was issued;
(d) Where there is a conflict between the written and printed provisions of the instrument, the written provisions prevail;
(e) Where the instrument is so ambiguous that there is doubt whether it is a bill or note, the holder may treat it as either at his election;
(f) Where a signature is so placed upon the instrument that it is not clear in what capacity the person making the same intended to sign, he is to be deemed an indorser;
(g) Where an instrument containing the word "I promise to pay" is signed by two or more persons, they are deemed to be jointly and severally liable thereon.