dtx

dtx is a file extension used in the TeX/LaTeX ecosystem for documented source files. A dtx file, short for documented TeX, combines human-readable documentation with TeX/LaTeX code in a single literate source. The standard workflow is to write the package as a dtx, then use the docstrip tool to extract the actual code into a .sty or .cls file and to generate a separate documentation file, usually a PDF or TeX document.

Dtx files are commonly associated with the LaTeX project and with the package authoring conventions from the TeX distribution. The documentation portion explains the package's purpose, commands, and usage, while the code portion contains the implementation. Portions of the source are marked for extraction by docstrip; these code blocks are removed from the documentation when producing the installation file.

To build a package, one typically runs latex on the .dtx to produce the rendered documentation, and runs latex on the .ins file (or uses a build script) to extract the code into the final package file(s) such as .sty or .cls. This approach supports both documentation and distribution from a single literate source, simplifying updates and versioning.

The dtx format remains widely used for traditional LaTeX packages, although newer tooling and packaging practices complement or supplant it in some projects. Notable examples include many core LaTeX packages that are distributed with both documentation and code in .dtx form.