@vhpk, since you affirmed the locant to plankk's question about the correct name, you have found a typographical error. Further, plankk has given you the outline of the correct nomenclature in that the 3 of 3-(prop-2-enyloxy)prop-1-ene is the locant of the substituent in parentheses. This is the same if we were discussing 3-chloroprop-1-ene. This is only slightly more complicated in that the name is nested in parentheses, e.g., 3-(2-chloroethoxy)prop-1-ene. The 2 of 2-chloroethoxy is the locant on the ethoxy substituent and the 3 refers to the propene.