With the large number of M functions, meaningful documentation is absolutely necessary in order to work efficiently with Power Query. This applies not only to native M functions, but also to custom M functions. This three-part blog series shows you how to provide custom M functions with a meaningful documentation and how to simplify your work considerably for yourself and all other users.
In the first article I explain why we need documentation. I will discuss the topic of metadata in M in general and explain why they are the key to my custom M functions‘ documentation. I then define a corresponding documentation and add it to my function.
Writing documentation for custom M-functions, Part 1
The second article explains a more flexibel way of defining metadata to document your custom function.
Writing documentation for custom M-functions, Part 2
This preparation serves the third and last part, in which I show how to document not only the function itself, but also the parameters in it.