I’m leaning thinking I should use backward Double-Slashes \ as the separator for ALL Tags, but would all players etc. like that?
So, any value that has multiple entries I just use the double-slash.
So, Genres would be separated by double-slashes, as well as ALL other Tags, Artist, ISRC #'s, etc.
Or should I do something different, like use double-slashes for some and a forward single-slash or semi-colon, etc. for others?
This has confused the crap out of me since ALL seem to be being used.
in my experience, it really depends on what software is looking at your tags.
in my case, I’ve settled on a semicolon ; for now, as MediaMonkey (on Android) supports those in genre and other tags. on the flip-side, Kodi defaults to a single forward slash /, but it can be set up to use other separators instead. I’m pretty sure I saw somewhere that a semicolon is very widely compatible, but it’s definitely not universal…
disclaimer: I’m still learning how these separators do (and don’t) work, this is just what I’ve personally found so far 
Thanks… Ya, so far my looking into this more and doing a ton of testing, it seems the Semi-Colon with a Space is the preferred choice, and that’s what I thought at first, then I got confused with how Mp3tag was doing things with double slashes, though without the space might be more compatible, the individual program can “add” the space if it wants like Windows Explorer does.
Anyway, still trying different variations.
As mentioned in another thread, Mp3Tag does not actually store a double backslash in the file, the double backslash is only how Mp3Tag displays that a tag has multiple values.
If you can use ID3v2.4, then you get proper multi-value support for tags without having to specify any separator. If you stick with ID3v2.3 use the separator that is supported by your software, both semicolon and slash are common choices. If the software does actually support multiple values. A lot of software doesn’t and only displays the tag value as is, in this case the choice of character boils down to personal preference on how you want to have it displayed.
Thanks for the thoughts guys…
After tons of testing with Picard and Mp3tag and seeing the results in those programs and Windows Explorer and MusicBee, and seeing what seems to be standard convention, I’ve decided I’m going to do a Forward Slash Separator on all my standard tags, no spaces, and then do a Semi-Colon with a Space for my Genre’s and multi-artists in the Artist Tag.
I’m using ID3 2.3…
This seems to be the best at displaying things properly, and what’s most used and how. I’ve tried every other variation and tags I could think to do, and there were often display issues.
I could just do ALL Semi-colon, but that doesn’t seem standard atm, and I can always change the separators in the future if I need to.
Thanks all for being sounding boards…
BTW, I’ve changed the above to using ALL “Semi-Colons” instead… Seem to be the better option.
I’m using Semi-Colon and Space for Multi-Artists, and Genres, and for all other Tags that might have multi-info I’m just using a Colon only… Trying that out.
Also, this is for ID3 2.3… 2.4 supports multi of the same Tag while 2.3 doesn’t, so you might need to have a different tagging system than me if you’re using 2.4. Now I just have to get the MusicBee Developer to fix his program, because it’s saving double slashes replacing my existing separators for any Tag that has multiple values, and it shouldn’t be when we are using ID3 2.3. It’s ruining all my tags.