While there are legacy and future standards for ID3 tags, the most popular version implemented today is ID3 version 2.3. A follow on version, 2.4, has not achieved popular status due to some disagreements on some of the revisions and the tremendous inertia present in the software and hardware marketplace. Full details of the ID3 standard can be found at http://www.id3.org/
ID3TagEd generally follows the 2.3 standard. A copy of the standard, taken from the id3 web site, may be viewed here. A new window will open.
Unicoded text
The v2 standard allows text frames to use unicode for the text - ID3TagEd now uses the Iconv module for all unicode decoding. If you are using NetSurf, then you will have the iconv module installed. If not, the latest version (as of 6th Aug 2014) can be downloaded from http://www.netsurf-browser.org/projects/iconv/. Note that, although ID3TagEd can decode frames in unicode format, any frames it creates or modifies will currently be written in Latin1 format.
If you do not have the Iconv module, ID3TagEd will still run but will be unable to decode any tags you load that already contain unicoded text.