the book is wrong. It first appeared in the forged screenplay in The Art of Star Wars, released in 1978, but it didnt make it into the 78 theatrical re-release. In fact, Episode V was the first time ppl saw an "episode" onscreen. Likely, they filmed the alternate Episode IV title at the same time as doing the titles for Empire in 1980. the 1981 release was the debut of Episode IV.