pic handling for indexed items

[simoncn]

(10-01-2017 16:45)aliasname Wrote:  I think I would have recoded my m4a (mp4 audio) albums if this format wouldn't have allowed me to add metadate incl. multiple pictures.

I tried adding an additional picture to an m4a file using iTunes. The picture was added but I didn't see anywhere to specify what the picture represented (e.g, artist picture, publisher picture, genre picture).