A form of technical writing

Technical writing

Technical writing, a form of technical communication, is a style of writing used in fields as diverse as computer hardware and software, engineering, chemistry, the aerospace industry, robotics, finance, consumer electronics, and biotechnology....

 and expository writing

Expository writing

Expository writing is a type of writing where the purpose is to inform, explain, describe, or define the author's subject to the reader. Expository text is meant to deposit information and is the most frequently used type of writing by students in colleges and universities. A well-written...

 "designed to convey to the reader how a change takes place through a series of stages" .

While the traditional process analysis and a set of instructions are both organized chronologically, the reader of a process analysis is typically interested in understanding the chronological components of a system largely without the reader's help (such as how the body digests an apple), while the reader of a set of instructions intends to use the instructions in order to accomplish a specific, limited task (such as how to bake an apple pie). By contrast, the reader of a mechanism description is more interested in an object in space (such as the form and nutritional value of a particular kind of apple).