APEL stands for "A Portable Emacs Library".
poe.el        | Emulate latest emacsen
poem.el       | Basic functions to write portable MULE programs
pces.el       | Portable character encoding scheme (coding-system) features
invisible.el  | Features about invisible region
mcharset.el   | MIME charset related features
static.el     | Utility for static evaluation
broken.el     | Provide information of broken facilities of Emacs
pccl.el       | Utility to write portable CCL program
alist.el      | Utility for Association-list
calist.el     | Utility for condition tree and condition/situation-alist
path-util.el  | Utility for path management or file detection
filename.el   | Utility to make file-name
install.el    | Utility to install emacs-lisp package
mule-caesar.el| ROT 13-47-48 Caesar rotation utility
emu.el        | Emu bundled in tm-7.106 compatibility
pcustom.el    | Provide portable custom environment
time-stamp.el | Maintain last change time stamps in files edited by Emacs
timezone.el   | Utility of time zone (Y2K fixed version)
product.el    | Functions for product version information