List of internal LaTeX2e macros
Martin Scharrer has compiled and published a list of internal macros defined in the LaTeX2e base files. While the extensive documentation “The LaTeX2e Sources” aka source2e covers LaTeX’s sources in depth, Martin Scharrers list gives a handy overview which may serve as an additional reference. It is designed for use by authors of classes or packages.
You can download this document
The author welcomes feedback by readers. If you would like to suggest improvements, write an email to him or post a comment on his web page.