extradefs – A miscellany of support macros
The macros work equally in LaTeX and Plain TeX; no documentation is available, even as comments in the file.
Maybe you are interested in the following packages as well.
- unouter: Suppress \outer flags in Plain TeX
- laps: Zero-width boxes for annotations, etc
- bibplain: Simple macros for using BibTeX with Plain TeX
- pitex: Documentation macros