Options :
...
-o filename : Output filename
Use # to specify position of numeric enumerator
Use % to specify source filename
Use $ to specify full source pathname
Use $$ to specify source folder name
I don't know if there is a way to 'escape' that interpretation, but doubling as required to escape some characters in a Windows batch file would be interpreted as a two-character numeric enumerator...
I don't know if there are any conventions for escape characters; a character that would be unlikely to be used in a file name might be a good choice (such as ^ or ~ perhaps?) or even a character that would be illegal in a (Windows) filename such as '>' if that is technically possible??
Consistentcy with any other escape use cases in NConvert would be desirable.
As '#' is a numeric enumerator that may, if I understand correctly, be included in code as '#' '##' '###' etc, any escape notation should if possible work for any representation...
As for the escape notation to be used, that is really outside my experience (I never expected even to use the command line... ) but I have presented some thoughts above that may or may not make sense.