Description:

APEL stands for "A Portable Emacs Library". It consists of
following modules:

poe.el - This is an emulation module mainly for basic
functions and special forms/macros of latest emacsen.
poem.el - This module provides basic functions to write
portable MULE programs.
pces.el - This module provides portable character encoding
scheme (coding-system) features.
invisible.el - This modules provides features about invisible
region.
mcharset.el - This modules provides MIME charset related
features.

and other some utility modules