I love outliners. I use OmniOutliner all the time (and used TAO before that).

I do sometimes use TM for a quick and dirty outline, just using tabs to mark levels. I wrote a bundle "Outliners" which exports a simple tab outline into various formats (HTML, Markdown, OPML, LaTeX... I forget what else) which is in the svn repository.

TM is not out of the box ready for outlining, but it has almost all of the needed functionality.

1. Folding could allow collapsing of outline pieces. I didn't follow the latest changes to folding technology, but it's possible that commands can either presently or in the future control folding so one could fold all items at a certain level.

2. Lines beginning with different tabs could be scoped as different levels and hence one could adjust the style sheet so lines began with bullets, etc. If the levels were defined in a nested way, i.e. outline.1, outline.1.1, etc., then I believe styles would even be inherited by sublevels cleanly.

3. Numbering could be done on a refresh basis, but I'm not sure it could be done live.

4. The big issue here is that there isn't currently a way for tabbed lines to be indented (i.e. lines always wrap to column 1). This is on Allan's To Do.

5. Commands to move bullets around the hierarchy seem straightforward to do, but would probably need to parse the whole document and would slow down with very large outlines. But I believe this would be very acceptable for 99% of documents.

6. Cloning seems much harder to do. Multiple columns seem like technically not an issue (tab delimiters), but likely a formatting disaster.

best wishes, Eric