The package defines macros that allow patching of existing commands, specifying those parts of the existing macro to be replaced, along with the replacements. Thus it provides more sophisticated manipulation than a package like patchcmd, which only permits modification by adding commands at the beginning or end of an existing definition.

The package is distributed in a relative of LaTeX doc format: it will run unmodified, though it benefits from docstrip treatment.

See also patchcmd etoolbox.

The author is David Kastrup. The package is Copyright © 1994 David Kastrup.