doc.tr is the updated source file for the nroff/troff User's Manual, with the new paragraphing features and various corrections. troffdoc.pdf was built directly from the source file (February 22, 2019 version). troffdoc-an.pdf is highlighted to show the differences between the February 22 and January 27 versions. troffdoc-20190127.pdf is the January 27, 2019 version. troffdoc-20190127-mk-an.pdf is the January 27 version with the changed lines flagged with gdiffmk. Additionally, changes have been highlighted so they are easier to find. changes.pdf provides a detailed description of the document changes for the January 27 and February 22 versions.