Devil is in the File Types
Gary B. Hoffman
In my last column, Sharing Genealogy Files,
I discussed the issue of transferring genealogical information from
one program to another. Some programs can read the files created by
others and most programs can read and write an intermediate file type
called GEDCOM. Many people who read that column e-mailed me with particular
questions about different file types they'd encountered. Most had received
a file and didn't know how to convert it. As a general rule, it's easier
to convert the file on the sending end than on the receiving end. That
is, the sender should take responsibility for giving the receiver a
file that the receiver can use.
Still, I wanted to be able to identify an originating program from
a given file name and file extension. So I asked Lance Dohe, current
president of the Computer Genealogy Society of San Diego, to dig up
all the file types for the many genealogy programs he has installed
on his computers. As a result of Lance's research, I can now make a
good guess about the program that belongs to a particular file. I'll
share our list with you in the table below (alphabetized by program
First, some background on file types. A file type is a merely a part
of the name of a file that extends to the right of the period, or dot.
The practice of using a file name extension actually preceded MS-DOS,
where it is optional. Most computer users know that DOS file names can
be up to eight characters in length and may have a three character file
extension after a period, which acts as a separator, such as "ARTICLE.TXT".
But while DOS doesn't really care about file extensions, programs do.
WordPerfect for DOS, for example, looked for files that had an extension
of .WP5 and opened them as its own. Lotus 1-2-3 wanted .WKS files, and
so on. Subsequent versions of the programs used variations of the file
type, such as .WK1, .WK2, etc.
the Message Boards
Windows introduced the idea of associations. A small database inside Windows
keeps track of file extensions and which programs they correspond to.
This allows you to double-click on a file and automatically trigger Windows
to start the correct program. Windows also shows you an icon for a file
depending on its associated file type.
Of course, Macintosh users are familiar with these actions. On a Mac,
all files have both a four-character file type as well as a four-character
"creator" which aren't part of the file names but are hidden
attributes of the files. The Mac's Finder program keeps track of file
types, creators, and icons in the Desktop Database, a hidden file. Sometimes
the desktop database gets corrupted and files don't open their parent
program. That's when Mac users need to rebuild the desktop by holding
down the Apple-option keys while rebooting.
Beginning with Windows 95, the file type extension on a PC is normally
hidden for types that Windows can associate with a program. When programs
ask for a file name, they automatically assign a file type and Windows
hides it from you in most views of files in a directory. To see the
file extensions, you can either select the Properties of a file or go
to the Views menu of a particular directory and de-select the option
to hide file types.
Because Windows now hides file extensions in most views, users
are becoming less aware of the file type designations for the
programs they use. The list below is offered as a guide only,
and is by no means exhaustive. I welcome additions and corrections
so that I can publish a more comprehensive guide to genealogy
file types in the future. Nonetheless, it's a good indication
of what you may run into when someone sends you a genealogy file.
To help me build this table of file types, Lance Dohe examined
files associated with each of the listed genealogy programs. In
most cases, we located all the files necessary to display one
family database. The asterisk (or "star") indicates
where a file name varies either by user command or program operation.
For some programs, the name portion is constant and the extension
Windows now hides file extensions in most views, users
are becoming less aware of the file type designations
for the programs they use.
of files, file extensions
|Ancestral Quest (PAF 2.31 compatible)
||7 *.DAT files
|Brother's Keeper (5.x for Windows)
||6 or 7 *.DT5 files; possibly 1 *.TXT file and 1 or more *.DTA
|Corel Family Tree
||5 *.TPS files
|Cumberland Family Tree
||25 files, a mixture of *.DAT and *.KO1
|Family Origins for Windows
||30 or more data files with no apparent order
|Family Records (4.x)
||up to 33 files, but generally:
18 TEMPLATE.* (extension varies)
1 CONFIG4.DAT configuration file
perhaps 4 NAMELIST.* (extension varies)
||1 *.IFT file
|Family Tree Maker (2.0 - 4.0 for DOS)
||1 *.FTM file
|Family Tree Maker (2.0 - 5.0 for Windows)
||1 *.FTW file (the only required file)
1 backup data file, *.FBK
possibly 1 compressed backup file, *.FBC
|Personal Ancestral File (PAF 3.0)
||2 files, *.LST and *.PAF
||10 files, 5 *.DB and 5 *.IDX
||about 10 files, a mixture of *.CDX, *.DBF, and *.FPT
|The Master Genealogist (3.x for Windows)
||36 - 46 files, a mixture of *.CDX, *.DBF, *.FPT
|Ultimate Family Tree
||about 30 files, a mixture of *.CDX, *.DBF, *.FPT
Gary Hoffman has
been involved in genealogy research for over 30 years. He is former president
of the Computer Genealogy Society of San Diego and is CGSSD's Webmaster. Currently
a computer manager at the University of California's San Diego campus, he recently
received a law degree and passed the California bar exam. His articles on technical
and legal issues relating to genealogy have appeared in several online publications
and newsletters and he is a regular speaker at national genealogy conferences.
© 1998 by Gary B. Hoffman. All Rights Reserved. Any republication
of this article requires the express consent of the author.