First Open your GRF Tool of choice, I used GRF Tool and GRF Factory (by timec0p).
To load the GRF data file, normally for the private server open the GRF for the particular server you are on, on your GRF extractor of choice choose the “open” option and find the RO folder with the GRF file. For instance if you are on CodedMarineRO, look for the CodedMarineRO.GRF file to extract the GAT and RSW files.
GRF Tool

GRF Factory

Once the GRF has loaded you will have a few files, but if you open a larger GRF there will inherently be more files, i.e. more *.rsw and *.gat files. In GRF Tool you can use “gat” to search without the quotation marks. In GRF Factory you can search with the wildcard symbol preceding the search string, so use “ *gat ”. Once you have narrowed down the files in GRF Tool you hit the column labeled “type” to sort the column, and in GRF Factory you don’t have to do anything because it has a better search/sort functionality.

Now once you have the GAT and RSW files selected use the “extract” function/button in each application. Save both types of files into a folder by themselves. Keep this safe because we will revisit this folder in a little while to create the FLD files.

To convert the GAT and RSW files I installed perl because using the start.exe, which is referenced in the FLD openkore guide did not work for me so I choose a full featured perl package.
Goto this website to choose a flavor of perl, I choose DWIM Perl:
http://www.perl.org/get.html#win32
****** Install perl ******
Or do this to install what I installed
To do it the way I did goto:
http://dwimperl.com/windows.html
Hit the BIG “DOWNLOAD” with the download arrow and unpack and install the perl version from the website.
Once it is installed to a location, let’s call it “C:\Dwimperl” follow these notes for installing and setting up this version of perl:
• directory that does not have spaces in it - e.g. c:\myperl\
• then run some commands and manually set some environment
[NOTE: RUN AT LEAST THE FIRST ONE]
variables:
c:\myperl\relocation.pl.bat ... this is REQUIRED!
c:\myperl\update_env.pl.bat ... this is OPTIONAL
Now to create the FLD files from the extracted files. The command to convert the RSW and GAT files will be simple because DWIM perl will register environment variables with the batch files you just clicked on above. Open the command prompt and now move to the directory where you have extracted the RSW and GAT files.
cd C:\GATandRSWfiles
First move the “gat_to_fld.pl”[/b][/color] file from “C:\openkore_ready\fields\tools” folder to the folder “C:\GATandRSWfiles” folder. Now you can run the script from the folder with the RSW and GAT files, which now have the correct perl scrip to convert them.
The script will be run using this now:
perl gat_to_fld.pl
Once this is done you are done and can go into “C:\GATandRSWfiles” folder and move the “ *.fld ” files to your openkore folder “C:\openkore_ready\fields”