NOTE:
With 3C you can code maps for CCD3, CC4 ,CC5, RTB and COI. If
you want to make a map for CC2. I would suggest using 5CC or
make a map with 3C using 3C and convert it to CC2 using Mafi's
CC2Tools program available at the CSO Map Making 'tools' section.
By
default 3C is set to code CC3 maps. (Which also codes COI maps)
So lets say you want to code your map for anything but CC3.
First off open 3C and you will have to open a tga or bgm in
order to accomplish out goal.

You
see below I'm opening a BGM, it actually isn't even the map
we are going to code, I just need a graphic open in 3C to facilitate
us

Now
the graphic is loaded I go edit/options as
shown below

Now
this is what we want! 'Element definition line'. Basically this
is what points to the coding file used to code either CC3,4,5
or RTB. (CC3 codes for COI) see shot below

Now
hot the browse button shown above.
You
will then see the screen below. The files we want to see are
cc3elem.ini,
cc4elem.ini, cc5elem.ini, and RTBelem.ini.
You
pick whatever file matches what version you want to code the
map for, and once highlighted hit OPEN in bottom right corner.

You
are now back here, simply click OK

Now
go to edit/Save options

DONT
START CODING YET!!
You
now close 3C. then open it up again and your ready to go! To
be safe check in Options to make sure the version you wanted
to code in has loaded properly, but if you have followed these
steps correctly, then your good. Otherwise.. its your fault
not mine! ;)