Indexing attributes that return collections?

[Cees De Groot]

Hi,

I'm busy cooking up something that'll index my mail archive. The first
step is just to throw all mails in a MagmaCollection, and index it on
date, message-id, sender/from/to/..., cross-reference it on
references, etcetera.

My easiest idea would be to have my mailmessage class (a simple
subclass of Celeste's mailmessage class) have, say:

references