Just for an additional note: the usual place to look for Greek and Latin abbreviations and ligatures is Thompson, "Introduction to Greek and Latin Paleography" (not the "Handbook to Greek Paleography"). In miniscule manuscripts and miniscule typography (e.g., Aldus), they are very, very common, and the list of abbreviations and ligatures is, as suggested already, very long. I've been writing something on just this issue just this past week. I would assume that they should be represented in electronic texts with their normalized values and marked up to indicate the ligatures in a higher protocol, and if exact representation is necessary, transform the markup to entities and use the PUA. Make sense to anyone?
Thanks.
