This section is just a FYI kind of section. We've started watching the work we are doing in the Query Editor begin appearing in the applied steps. As we continue working in this chapter, we'll be reviewing and editing the applied steps. As we perform a task that gets recorded as a step, we are actually updating the Power Query Formula Language known as M. M is a bit of an informal name, and it stands for mashup, because we are mashing up data.
The probability is that you'll never need to do anything with the M expression. However, to be on the safe side, let me show you where it is located.