Notes are for translations (hence "Add translation") or better identifying the characters when there is several in the image.

This does not mean every image can have character notes though:

  • post #101275 - the lack of faces makes it hard to tell who is who without them
  • post #22313 - the sheer number makes it time consuming to check each tag to work them all out for yourself
  • Occasionally the appearance of several minor or new characters will result in notes to facilitate identifying them in the future. Usually a Contributor/Privileged or Mod will add these though.