I would like to search for digits in a tagfield. If the digits are followed by characters or the digits are behind characters, I want to make a white space between the digits and the characters.
In RegxBuddy this works:
Match: (\d)(?=[a-zA-Z])|([a-zA-Z])(?=\d)
Replace: \0
But If I try to enter this on Mp3Tag, the result is really strange... 
How do I make a back reference in Mp3Tag?
As written in the help $N is used to get the reference:
Replace: $0
Works great! Thanks for this important information. 
Is this $0 something special for Mp3Tag?
According to my Regex-documentation 
, the $n is a "reference capture" and the \0 a "numbered backreference" - not exactly the same.
Which regex-dialect is used by Mp3Tag?
\N (e.g. \1) can be used to reference the Nth sub-expression.
It's Perl syntax.