The XDG Base Directory
Specification<http://standards.freedesktop.org/basedir-spec/>provides
some common paths in user's home to store personal application
configurations, or, using their own words "*defines where these files should
be looked for by defining one or more base directories relative to which
files should be located*".

XDG Base Directory Specification allows efficient backup, in which you can
easily choose to backup your data and/or your configuration files for
instance. An application could easily propose such backup for the whole
system if all applications were matching these specification.

Therefore, although I think that this bug/enhancement is not vital, it would
be great for Emacs to be "FreeDesktop XDG Base Directory Specification"
compliant.

Currently Emacs is using "$HOME/.emacs.d/". This is what XDG basedir spec
defines:

   - $XDG_DATA_HOME (usually $HOME/.local/share/) as "*the base directory
   relative to which user specific data files should be stored*"
   - $XDG_CONFIG_HOME (usually $HOME/.config/) as "*the base directory
   relative to which user specific configuration files should be stored*"
   - $XDG_CACHE_HOME (usually $HOME/.cache/) as "*the base directory
   relative to which user specific non-essential data files should be stored
   *"

(http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html)

In order to make Emacs XDG basedir compliant, I think that it would be nice
to use:

   - $XDG_CONFIG_HOME/emacs  ;;for "init.el" and storing customize
   configuration


   - $XDG_DATA_HOME/emacs  ;;for sessions and backups


   - $XDG_CACHE_HOME/emacs  ;;for cache files

Or maybe some other distribution. What do you think about it?

There's a small C library that may be useful check it out, written for the
sole purpose of xdg basedir spec compliance:
https://n.ethz.ch/student/nevillm/download/libxdg-basedir/