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.
- redefine: Conditional macro, etc., definitions
- defstring: Define macros as verbatim macros
- getoptk: Define macros with sophisticated options
- font-change: Macros to change text and mathematics fonts in plain TeX