The Heirloom Documentation Tools provide troff, nroff, and related utilities to format manual pages and other documents for output on terminals and printers. They are portable and enhanced versions of the respective OpenSolaris utilities, which descend from ditroff and the historical Unix troff. troff provides advanced typographical features such as kerning, tracking, and hanging characters. It can access PostScript Type 1, OpenType, and TrueType fonts directly. Internationalized hyphenation, international paper sizes, and UTF-8 input are supported.