 The plural term is often used of a single document because of the influence of the Latin term, since in that language "litterae", which literally means letters (of the alphabet) can also mean a letter (in the sense of message).Before the entry into force of the Code of Canon Law in 1917, the term had a wider sense (see the article in the Catholic Encyclopedia of that period).The conditions for issuing dimissorial letters were also different and were more complicated.