xetex – An extended variant of TeX for use with Unicode sources

X∃TeX is a TeX type­set­ting en­gine us­ing Uni­code and sup­port­ing mod­ern font tech­nolo­gies such as OpenType, TrueType or Ap­ple Ad­vanced Ty­pog­ra­phy (AAT), in­clud­ing OpenType math­e­mat­ics fonts. X∃TeX sup­ports many ex­ten­sions that re­flect its ori­gins in lin­guis­tic re­search; it also sup­ports mi­cro-ty­pog­ra­phy (as avail­able in pdfTeX). X∃TeX was de­vel­oped by the SIL (orig­i­nally for those study­ing lin­guis­tics, and us­ing Mac­in­tosh com­put­ers).
X∃TeX’s im­me­di­ate out­put is an ex­tended sort of DVI for­mat, but it is or­di­nar­ily pro­cessed by a tightly bound xd­vipdfmx pro­ces­sor, that pro­duces PDF.
X∃TeX is de­vel­oped as a part of TeX Live; doc­u­men­ta­tion has arisen sep­a­rately.