NetNewsWire imports and exports OPML subscriptions lists.

It doesn't currently understand nested subscriptions lists, but that
will change. (It will both import and export nested lists.)

***Importing

It tries to be as forgiving as possible in what it accepts. It ignores
case. For the name of a feed it first looks at the text attribute, then
at the title attribute. For the home URL of a feed it looks at htmlUrl
then at url.

If an RSS URL doesn't exist, it does RSS auto-discovery to try to find
the feed. (This makes it possible to import blogrolling.com OPML files,
for instance.)

***Exporting

It exports using ISO-8859 encoding, since that's most likely to be
compatible (with Radio and with Windows aggregators).

It sets the following attributes:

text -- name of feed
title -- name of feed (redundancy for compatibility sake)
description -- description of feed
type -- rss
version -- RSS (more redundancy for compatibility sake)
htmlUrl -- URL of home page
xmlUrl -- URL of feed

***Sample OPML file

http://ranchero.com/downloads/MySubscriptions.opml

-Brent