The package provides the switch \ifetex which indicates whether
e-TeX is available or not. The package can be loaded as LaTeX
package using \usepackage{ifetex} or in plain TeX using \input
ifetex. In either case it aborts silently if the \ifetex macro
is already defined. The package's test is whether \eTeXversion
is defined as a primitive; if it is, the package assumes e-TeX
features are available.
