An extended version of TeX (which is capable of running as if
it were TeX unmodified). E-TeX has been specified by the LaTeX
team as the engine for the development of LaTeX2e, in the
immediate future; as a result, LaTeX programmers may (in all
current TeX distributions) assume e-TeX functionality. The
pdftex engine directly incorporates the e-TeX extensions. The
development source for e-TeX is the TeX Live source repository.
