EXE, PDF, DLL, TXT not supported?

[JimmyJohns]

Trying to mess with my metadata on different file types. So far have tried an EXE, a PDF, a DLL, a TXT, and none of them work and all say "Error: Writing of 'exe/pdf/dll/txt' files is not yet supported". This is kind of weird considering they're some of the most popular file types. Do you plan on adding support for them in the future?

[StarGeek]

PDF files are editable, but it's impossible to say what the problem is without seeing your exact command and the output.

The other three don't have any metadata that is really editable to begin with.  A TXT file, for example, is just plain simple text.  There isn't any metadata standard to cover it.  The others are compiled programs.  Any changes there would have to be done to the source code before compiling.

What kind of things are you trying to do with EXE/DLL/TXT files?