convert - special characters in file name

Hello all,

I am running GraphicsMagick 1.3.22 compiled from source by me with MinGW 
on Windows.

If the input file name starts with the "at" sign (@), for example 
@test.tif, convert fails with `Unable to open file (II*) [Invalid 
argument]'. IF the file name is @pvn01!.tif then the message is `Unable 
to open file (pvn01!.tif) [No such file or directory]'.

I found the following paragraphs at 
http://www.graphicsmagick.org/GraphicsMagick.html

...
When running a commandline utility, you can prepend an at sign @ to a 
filename to read a list of image filenames from that file. This is 
convenient in the event you have too many image filenames to fit on the 
command line.
...

This explains the first error message but not the second, especially 
since test.tif is a copy of @pvn01!.tif.

1) What is going on with the @?
2) Are there other special characters that are legal in Windows 
filenames that cause trouble for convert?

I worked around the problem like this:
`gm convert .\@pvn01!.tif test.pdf'
but I may not have that option with special characters within the file name.

Regards,
Test User.