TYPO3 Core

The `eID` handler system dates back to the time `PSR-15`
middlewares where not a topic and TYPO3 needed to provide
extension authors a way to do request working before the
normal content rendering, which also required to do custom
bootstraps as most things are not build at that early time.
Going even more back in history that includec the way to
use dedicated scripts directly - which has been banned for
good already.

Since the introduction of the PSR-15 middleware stack using
`eID` handler became nearly obsolete and `eID` handler could
be replaced with a middleware.