This section is used to set the FORMAT for a generated group. Some compilers will not allow the specification of files separated with spaces and a prefix must be used. For Borland's compilers if you want to create a library you must add the objects to the library with the prefix "+" as in: TLIB LIBRARY.LIB +FILE1.OBJ +FILE2.OBJ +FILE3.OBJ.
EXAMPLE: If you create group FGO=.obj in section "FileGroups" and here you set key FGO=+%s, a group will be generated with the content FGO=+file1.obj +file2.obj, etc.
In special cases you may need to set one format for the first file and another format for the next file(s).
EXAMPLE: Your linker expects object files separated with "," but "," must only be between object files as in: "LINK OBJ1.A,OBJ2.A,OBJ3.A EXE". If you need to do this add to FileGroups a section FGA = .A; and to the GroupFormats section add these two keys: FGA0=%s FGA=,%s where %s represents a filename.
These settings ensure that if you have only one file in the project first the FGA0 format will be used (format without ",") and if you have other files, FGA will be used. You can use it also for cases where a prefix must be set before the first file, as in: "LINK /objs:ob1,obj2,obj3". In this case you would set FGA0=/obj:%s and FGA=,%s. If some group has no format set here the default (%s) is used.