The /opt/freecalypso host directory tree used by the present FC host tools
package and by various add-ons to it does NOT follow the traditional Unix/Linux
file system hierarchy standard (FHS), instead it is a highly specialized
directory tree that is meant to be private to FreeCalypso, with its structure
defined solely by the Mother and no one else.  The following subdirectories are
currently defined:

aud-*: these directories appear if you install our optional
fc-audio-config package, and contain subtrees to be uploaded by
production line scripts into target device FFS under /aud via fc-fsio.

batteries and charging: these subtrees come from fc-battery-conf
(optional just like fc-audio-config) and are meant to be used with
fc-fsio write-battery-table and write-charging-config commands.

bin and include are the only subdirectories under /opt/freecalypso
which follow traditional UNIX directory layout; include was added so
that packages external to the core FC host tools package like
fc-rfcal-tools and freecalypso-ui-dev can use rvinterf headers.

gcc: the recommend install location for our ARM7 gcc toolchain is
/opt/freecalypso/gcc.

helpfiles subdir contains help files for those FC host utilities which
implement a help command.

loadtools subdir contains hardware parameter files and init scripts
which underlie the all-important -h option to fc-loadtool, fc-iram and
fc-xram, collectively known as loadtools.

rfcal subdir only appears if you are doing RF calibration and install
fc-rfcal-tools, and some of the necessary config files under that
subdir you have to create yourself using your own RF knowledge specific
to your particular setup.

scripts subdir contains command scripts for FC host tools other than
fc-loadtool, currently for fc-fsio.

sim-data and sim-scripts subdirectories are used by the FC SIM tools package.

target-bin contains ARM7 target binaries used under the hood by
loadtools.

The basic minimal form of the /opt/freecalypso tree is populated when
you install FC host tools, but it is further enriched if and when you
install further add-ons (fc-audio-config, fc-battery-conf,
fc-rfcal-tools) which are more specialized and not required for all
users.  I expect to have more additions in the future: for example,
when we start using the Melody E1 mechanism in our planned FC Libre
Dumbphone, there will be a FreeCalypso ringtones package that will
install E1-format melody files somewhere under /opt/freecalyso, to be
subsequently uploaded into the actual phones via fc-fsio, initially at
production time and optionally by end users.