The original LEDMAC package for typesetting critical editions, by Peter Wilson, March 2003.
This LaTeX package is placed here for the record and to preserve the history of an important piece of typographic software. It should be noted that LEDMAC still works well, if the feature-set meets your needs.
In March 2003 Peter Wilson started what he called "an attempt" to port EDMAC from TeX to LaTeX. The starting point was EDMAC version 3.16 as documented on 19 July 1994 (available from CTAN and now Github). The port was very successful. At the time of writing (2021), I still use LEDMAC for several projects.
The main documentation file in this repo is ledmac.pdf.
See the Github EDMAC repo for further documentation on the history of this package and its post-LEDMAC development.
Peter Wilson is perhaps best known for authoring the influential Memoir package. Peter has also originated or contributed code to almost 100 other TeX macro packages. Dave Walden conducted a fine interview with Peter in 2006 that can be read on the TUG website.