Illegal characters in filenames (under Windows)

When using the auto-naming macros (%%t and the like) in OGGENC, there are cases
when a character is invalid in the filename, but of course legal in the comment.
An example:
oggenc -N "04" -b 192 --artist="Frank Zappa" --title="Waka/Jawaka"
--album="Waka/Jawaka" -d "1972" -n "%%n %%t.ogg" track04.wavresults in: ERROR:
cannot open output file "04 Waka/Jawaka.ogg"
I suggest that invalid characters should be replaced with an underscore instead.
According to http://linux-ntfs.sourceforge.net/ntfs/concepts/filename_namespace.html
the following characters are not allowed under Win32:
------
 Win32 is a subset of the POSIX namespace and is case insensitive. It uses all
the Unicode characters, except: '"' '*' '/' ':' '<' '>' '?' '\' '|' N.B. Names
cannot end with Dot '.', or Space ' '.------