Online virus scans from BitDefender, Kapersky, McAfee, and Panda identified file C:\WINDOWS\SYSTEM32\TFTP4044 on my PC as a W32/Blaster.worm.a.
(Norton did not.)

I tried submitting the file to the ClamWin database, but was told that it was already in the database as a "broken executable". What exactly is that?

clamscan.exe successfully detected this "broken executable" when I ran it from either a batch file or the command line, when I specified (as shown in clamscan --help):

--detect-broken Try to detect broken executable files

as in:

clamscan.exe --quiet --bell --detect-broken --recursive --database="C:\Documents and Settings\All Users\.clamwin\db" --tempdir="\ClamWin\tmp" %1

Can I somehow specify to use "--detect-broken" in my ClamWin.conf file? If so, how?

The "Example config file for the Clam AV daemyes" at https://www.sosdg.org/clamav-win32/clamd.conf (and elsewhere) has the following:

# With this option clamav will try to detect broken executables and mark
# them as Broken.Executable
# Default: no
#DetectBrokenExecutables yes

but apparently ClamWin.conf uses a different format.

Thank you for any information you can provide.

broken executable is a file with damaged executable header and most likely it will not run anyway (don't try on a live system though)

clamd.conf is for clamav background service (daemon) which is not part of clamwin.

I will add --detect-broken to clamwin's options (beta will be released soon)

Thank you for the clear, concise explanation of the term "broken executable".

I just looked at the parent directory of the clamd.conf file I referenced, and it looks like this particular one is for ClamAV for Win32 -- which is apparently a command-line only CygWin interface to ClamAv.

Thank you for putting addition of the "--detect-broken" option into clamwin's options in your plans. I appreciate that.

With that, and with the ClamWin Antivirus Glue for Firefox (https://addons.mozilla.org/extensions/moreinfo.php?application=firefox&category=Privacy%20and%20Security&id=771), I may ultimately be able to eliminate my need for a commercial antirivus program.

Thank you.

actually broken-executable in clamav is slightly broader then just damaged exe header. Basically any file that does not have proper PE (Portable Executable) file structure, more info here:
https://win32assembly.online.fr/pe-tut1.html

It can be a file that hasn't been fully downloaded or damaged in transit, etc It is unlikely that windows will execute such file