individual index_formats

[Hanspeter Roth]

Is it possible to have lines with different index_formats in the
index? I would like to display a different date format for messages
sent within the last 24 hours.
I tried:

folder-hook .  \
  'set index_format="%4C %Z %{%b %d} %-15.15F (%4l) %s"'
message-hook '~d <1d' \
  'set index_format="%4C %Z %{ %H:%M} %-15.15F (%4l) %s"'

But I had no luck.

-Hanspeter