Thanks to all of you. I did misunderstand. I needed artwork in my MP3
file.
Is iTunes:image tag strictly for iTunes Music Store display?
As for my MP3 file, iTunes accepted an appropriate GIF (copied from the
web) and added it to the MP3 file. All good.
That leads to two related image questions--
1) is there a way to have iTunes (desktop) show an image for the
"podcast" subscription itself?
Can't say I've seen this with any reliability. Does seem to happen
with http://www.nyas.org/podcasts/nyaspodcast.xml
Doesn't seem to happen with other podcasts.
However, again that may be a misunderstanding.
Is iTunes just display artwork based on last item played for a
subscription?
2) Is there a way to set artwork for an MP4 video file?
iTunes seems to show something from the video, but not sure where
in the clip.
Is there an MP4 poster frame?
Do I need to be sure the beginning / end is a poster equivalent?