QUOTE (DetlevD @ Aug 13 2011, 15:52)

Hmm, it's good to know that you are a rather close step away from using a perfect application.
It looks like that you need only to change one character to solve the task by changing a genre text string from "Folk-Rock" to "Folk/Rock".
But ... because you want this to do on the genre tag field within a ID3v1 tag, you might have to change the world.
Please read there about the technical standards regarding the ID3v1 tag.
Follow the links on these pages to the list of genres in ID3v1.
http://en.wikipedia.org/wiki/ID3http://de.wikipedia.org/wiki/ID3-Taghttp://de.wikipedia.org/wiki/Liste_der_ID3v1-GenresTo make it short ... the ID3v1 genre tag-field is only a 1-byte index into a list of genre names.
So the genre number 81 is set to "Folk-Rock", first implemented by WinAmp.
This list and the spelling of names within this list has been raised to worldwide common sense.
You might have a closer look to all of your other mp3 programs what is going wrong there when the ID3v1 genre tag number 81 is displayed as the name "Folk/Rock".
It is possible for you to work with the ID3v2 tag standard?
There is no such restriction of a limited list of pre-defined genre names.
DD.20110813.0753.CEST
This is truly perplexing because I've been editing my mp3 tags for over 10 years now and this is the first time I've seen Folk-Rock and not Folk/Rock in the drop down Genre box (I've used a lot of programs for this over the years).
But as you say,
"So the genre number 81 is set to "Folk-Rock", first implemented by WinAmp."
this is the correct convention for the Genre which I will be using from now on

It seems the only program I use which Folk-Rock will remain a little flawed in is WinAmp itself.
When I view file info the IDv2 Genre shows Folk-Rock but the IDv1 Genre Shows Folk/Rock lol
Thank you very much for the feedback and I'll be donating a little towards Mp3tag right now.
Now a perfect program, Thanks