The Tiro fonts are super, and I hadn't paid attention to them before. Thanks! They are licensed under the
Open Font License, so anyone can download, distribute and use them for any purpose.
The Microsoft fonts, including Arial Unicode, have always been covered by a completely restrictive commercial license. The font files (TTF, OTF) may not be downloaded or distributed. The fonts are licensed as integral parts of the Windows OS and may be used only in that environment only by people who have paid for a Windows license. Most people, including major publishers, think that Arial Unicode is a free font. It's not. Yes, a PDF with some characters embedded in it can be shared, but not the font itself.