In jazz, there’s a common method to get from one place in a progression to another. It’s called the two-five device (really it’s ii-V, but I want to convey that that it’s pronounced “two-five”). In music theory, the five chord wants to resolve to the one or the tonic, that is, the key that the song is in.
Coltrane found a way to get back to the tonic by using a series of ii-V devices that go up minor thirds. This method of moving around is called a Coltrane change. It sounds complicated, but just know: it’s a way to move around in a song and still get where the song needs to go. A Coltrane change is just a series of chord substitutions, and using substitutions is a common device used in jazz.
Coltrane changes remind me that no matter how well I design a documentation set, there are people who find things differently than I expect them to. I need to account for my readers by offering alternative ways to get to the content they want. They can use the TOC or an index. However, most readers won’t use these archaic methods. Most of my readers will be using search or links. So I try to give them richer links and better search metadata, the ii-V of documentation.