In the discrete branches of mathematics and the computer sciences, it will only take some seconds until you're faced with a set like {1,...,m}. Only some people write $1\ldotp\ldotp m$, or $\{j:1\leq j\leq m\}$, and that journal you're submitting to might want something else entirely. \otm{} provides an interface that makes changing from one to another a one-line change. The author is Ulrich M. Schwarz.