In the Engineering model, meanwhile, plain text files are at the center of your work. The most “real” thing in your project will either be those files or, more likely, the Git, Mercurial, or SVN repository that controls the project. Changes are tracked outside the files. Data analysis is managed in code that produces outputs in (ideally) a known and reproducible manner. Citation and reference management will likely also be done in plain text, as with a BibTeX .bib file. Final outputs are assembled from the plain text and turned to .tex, .html, or .pdf using some kind of typesetting or conversion tool. Very often, because of some unavoidable facts about the world, the final output of this kind of solution is also a .docx file.