Physical File "G" fields - Hope I have the correct list

If I have the wrong list please forgive and push to correct one.

When using the Client Access Express Data Transfer Excel add-in I can
automatically create a physical file on the iSeries. However, most of
the fields show are created show a "G" data type format.

Questions:
1. How does one read such a field. My COBOL program is erroring out.
2. When creating the iSeries PF I have attempted to make Character
fields that are the correct length. Then run a dummy download from the
iSeries to the PC creating me a FDF file. That FDF file does not work
when I try to upload from the EXCEL spreadsheet using the Express Data
Transfer Excel Add-in.

Not sure what I am missing.

Thomas