The primary author of the text must understand what is to be communicated AT LEAST as well as the target audience. If you are supposed to write a user manual fo

The primary author of the text must understand what is to be communicated AT LEAST as well as the target audience. If you are supposed to write a user manual for the next iPhone, the main trick is not technical, but rather to figure out of to structure relatively simple information in a way that even your mother can understand. Still, it's probably a good idea to have an engineer go over the text after, to make sure there are no glaring errors. If on, the other hand, you write documentation for Apache Spark, you probably need to be a pretty competent computer scientist, data engineer or data scientist. Maybe a tech writer can go over the text after, but they will probably not be able to understand the content, so can do little beyond formatting, language and structure (and even that needs to be reviewed by a real tech person after). In the latter case, it may be VERY useful for the tech person to have some formal training in technical writing, in addition to be the kind of engineer that is also pretty good with language and presentation.