How can I form XFD index from cobol data file

I've recently working on a project to form a index in manually in XFD file
From Acucobol Vision file.

Can someone who understand what is mean by first index, second index, condition and the rest.

My XFD structure form manual where I found but I still doesn't understand from its structure.Can someone explain for me in details for below
Code:

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# This xfd layout is a generic one suitable for accessing any
# .DAD file. However, it needs to be copied and amended for each
# DAD file that you wish to get access to.
# The simplest scenario is that you copy dad.xfd to a new file
# with the same name as the database you wish to access and extension .XFD
# Then edit this new file and replace the two instances of 'FILE' with the
# filename that you want to access. e.g. if you want to have ODBC access to
# icvc.dad then copy dad.xfd to new file icvc.xfd and change line
# XFD,02,FILE,FILE to be
# XFD,02,ICVC,ICVC
#
# If this doesn't work then the database file you are trying to access has
# probably set different values for search index sizes. The easiest way to
# check this is to run $list for the database that you want to access and
# note down all the key information that it gives. If that is different
# to the key info in this file then you need to modify the xfd file to match
# In the current xfd there are four indexes defined. In all cases the first
# index will be correct and so should the third index. However, the other
# two may need to be modified or removed if not present.
# Index 4 is optional and is not present if the database is rebuilt without
# the fast list option.
# explaining the details of 2nd index. 1 st line consists of 8 values separated
# by commas. The first value of 3 is how many segments the index consists of.
# second value 1 means duplicates allowed (0 means NO DUPS).
# The remaining six fields are three pairs of key size and byte offset, e.g.
# first index segment is 4 bytes long and starts from byte 4, second index
# segment is 20 bytes long and starts from byte 21 etc.
# The second line specifies how many field names there are to follow and lines 3
# to 5 are the three field names as defined lower in this xfd. For instance
# if you look at field D1UNIQ you will see it is defined as starting from byte 0
# and is 4 bytes long. This corresponds to the values entered in the key definition.
#
XFD,02,ICVC,ICVC
00300,00041,004
# [Key Section]
# [1st index]
01,0,013,00000
04
D1UNIQ
D1NAME
D1NAMX
D1OCCU
# [2nd index]
3,1,004,00004,020,00021,004,00000
03
D1NAME
D1TUPP
D1UNIQ
# [3rd index]
3,1,004,00004,008,00013,004,00000
03
D1NAME
D1NUMB
D1UNIQ
# [4th index]
1,1,020,00021
01
D1TUPP
# [Condition Section]
000
# [Field Section]
0015,00015,00016
00000,00013,16,00013,+00,000,999,D1KEY
00000,00004,12,00009,+00,000,000,D1UNIQ
00004,00004,16,00004,+00,000,000,D1NAME
00008,00001,16,00001,+00,000,000,D1NAMX
00009,00004,12,00009,+00,000,000,D1OCCU
00013,00008,11,00018,-06,000,000,D1NUMB
00021,00040,16,00040,+00,000,000,D1TUPP
00061,00001,01,00001,+00,000,000,D1GRAD
00062,00004,12,00008,+00,000,000,D1DLUP
00066,00004,12,00008,+00,000,000,D1TLUP
00070,00004,16,00004,+00,000,000,D1OLUP
00074,00001,16,00001,+00,000,000,D1TYPE
00075,00002,16,00002,+00,000,000,D1FORM
00077,00160,16,00160,+00,000,000,D1TEXT
00237,00001,16,00001,+00,000,000,D1PRIN
00238,00062,16,00062,+00,000,000,D1FILL

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I knowed Acucorp come out with one tool known as Acucorp Indexed file record editor, short form is named as alfred. I know it will used to check out structure of cobol data file. By the way, is that have any replacement tool or other free record editor which can help us to inspect record format of cobol data file?

Thanks if anyone could help my question.